Next release of cmake will choke by default if minimum version < 2.8.12

Since 425da070 LWS_PTHR_FLAGS is no longer
used, so just remove it.

afunix.h doesn't exist on mingw.

It doesn't work with 4.3.3

    https://github.com/warmcat/libwebsockets/issues/2034

Prior to 4.4, -Wuninitialized could only be used with -O.

Event lib support as it has been isn't scaling well, at the low level
libevent and libev headers have a namespace conflict so they can't
both be built into the same image, and at the distro level, binding
all the event libs to libwebsockets.so makes a bloaty situation for
packaging, lws will drag in all the event libs every time.

This patch implements the plan discussed here

https://github.com/warmcat/libwebsockets/issues/1980

and refactors the event lib support so they are built into isolated
plugins and bound at runtime according to what the application says
it wants to use.  The event lib plugins can be packaged individually
so that only the needed sets of support are installed (perhaps none
of them if the user code is OK with the default poll() loop).  And
dependent user code can mark the specific event loop plugin package
as required so pieces are added as needed.

The eventlib-foreign example is also refactored to build the selected
lib support isolated.

A readme is added detailing the changes and how to use them.

https://libwebsockets.org/git/libwebsockets/tree/READMEs/README.event-libs.md

Presently a vh is allocated per trust store at policy parsing-time, this
is no problem on a linux-class device or if you decide you need a dynamic
policy for functionality reasons.

However if you're in a constrained enough situation that the static policy
makes sense, in the case your trust stores do not have 100% duty cycle, ie,
are anyway always in use, the currently-unused vhosts and their x.509 stack
are sitting there taking up heap for no immediate benefit.

This patch modifies behaviour in ..._STATIC_POLICY_ONLY so that vhosts and
associated x.509 tls contexts are not instantiated until a secure stream using
them is created; they are refcounted, and when the last logical secure
stream using a vhost is destroyed, the vhost and its tls context is also
destroyed.

If another ss connection is created that wants to use the trust store, the
vhost and x.509 context is regenerated again as needed.

Currently the refcounting is by ss, it's also possible to move the refcounting
to be by connection.  The choice is between the delay to generate the vh
being visisble at logical ss creation-time, or at connection-time.  It's anyway
not preferable to have ss instantiated and taking up space with no associated
connection or connection attempt underway.

NB you will need to reprocess any static policies after this patch so they
conform to the trust_store changes.

The old esp32 -factory stuff along with the lws support doesn't have a
future in its old form.  It has users but the ratio of effort to
contribution is really especially bad.  I haven't updated it for more
than a year since esp-idf changes broke the original stuff.

Freertos plat is alive and well and getting a lot of new use, ESP-32 is
supported both there and by modern lws_drivers pieces, including in CI
on real hardware, any further effort will be invested in that direction
instead of more vendor api-specific code (outside of wrapper
implementation).

lws_drivers wraps any SDK apis in generic lws apis such that your code
just uses those, enabling it to become SDK / SoC / vendor independent.
Its first implementation is on esp-idf, the low and mid-level features
that were in the old -factory are already available using that and
new technologies like lws_struct and Secure Streams.

As far as I know there are no users of this, although it worked
it's basically unmaintainable due to handling the sql and JSON
manually.

Gradually better capabilities have appeared in lws, like
lws_struct abstracting out the sql and JSON, and now generic
JWT... these have been used in Sai to great effect and displaced
the only organic would-be user of this.

There is a better path to do this stuff now and no point keeping
this around.

 - Add low level system message distibution framework
 - Add support for local Secure Streams to participate using _lws_smd streamtype
 - Add apit test and minimal example
 - Add SS proxy support for _lws_smd

See minimal-secure-streams-smd README.md

Make a start on generic peripheral and bus drivers to provide
meta-functionality regardless of platform.

On the one hand this simply provides...

 - bitbang i2c on top of esp-idf gpio apis
 - ssd1306 oled chip driver as found on Heltec WB32
 - modifications to the minimal example test for esp32 to use that

... on the other hand, those capabilities are provided by creating:

 - an abstract i2c class object
 - an abstract gpio class object
 - i2c class implementation using the abstract gpio for bitbang
 - an abstract display class object
 - an abstract display state (brightness, animated change,
    on/off/init tracking, autodim after inactive, auto-off /
    blanking after inactive)

... with the intention, eg, you only have to add a platform
implementation for the gpio to be able to use the i2c-based
display drivers and state handling, and i2c bitbang, without
any other modifications.

LWS_EXTERN needs to be empty for windows when declaring functions in the
headers.  But for data, it needs the explicit extern otherwise on windows
or mingw based builds, it thinks we are redeclaring the data each time.

Adapt the pt sul owner list to be an array, and define two different lists,
one that acts like before and is the default for existing users, and another
that has the ability to cooperate with systemwide suspend to restrict the
interval spent suspended so that it will wake in time for the earliest
thing on this wake-suspend sul list.

Clean the api a bit and add lws_sul_cancel() that only needs the sul as the
argument.

Add a flag for client creation info to indicate that this client connection
is important enough that, eg, validity checking it to detect silently dead
connections should go on the wake-suspend sul list.  That flag is exposed in
secure streams policy so it can be added to a streamtype with
"swake_validity": true

Deprecate out the old vhost timer stuff that predates sul.  Add a flag
LWS_WITH_DEPRECATED_THINGS in cmake so users can get it back temporarily
before it will be removed in a v4.2.

Adapt all remaining in-tree users of it to use explicit suls.

Add Sai for openssl-v3 and for boringssl

Allow selection of Unix Domain Sockets on windows since it is supported
for the last couple of years on windows 10

https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

... if only they could add a full set of posix pieces to go with it
(and abstract namespace UDS which doesn't work apparently) so that
the parts dealing with uid / gid don't have to be disabled.

https://github.com/warmcat/libwebsockets/pull/1926



Signed-off-by: Jakov Smolic <jakov.smolic@sartura.hr>

Establish a new distributed CMake architecture with CMake code related to
a source directory moving to be in the subdir in its own CMakeLists.txt.
In particular, there's now one in ./lib which calls through to ones
further down the directory tree like ./lib/plat/xxx, ./lib/roles/xxx etc.

This cuts the main CMakelists.txt from 98KB -> 33KB, about a 66% reduction,
and it's much easier to maintain sub-CMakeLists.txt that are in the same
directory as the sources they manage, and conceal all the details that that
level.

Child CMakelists.txt become responsible for:

 - include_directories() definition (this is not supported by CMake
   directly, it passes it back up via PARENT_SCOPE vars in helper
   macros)

 - Addition child CMakeLists.txt inclusion, for example toplevel ->
   role -> role subdir

 - Source file addition to the build

 - Dependent library path resolution... this is now a private thing
   in the child CMakeLists.txt, it just passes back any adaptations
   to include_directories() and the LIB_LIST without filling the
   parent namespace with the details

Esp-idf has an improved but still kind of abused cmake-
based build system now.

If we see ESP_PLATFORM coming as a cmake var, we can know we
are being built from inside the esp-idf config system.

Leave the existing esp32 arrangements alone but triggered off
ESP_PLATFORM, adapt to use the cross toolchain file and
various quirks automatically.

In this way you can build lws a part of your project in a
much cleaner way.

Prepare a minimal esp32 test app for use in Sai

Adapt .sai.json to build for esp32

Replace the bash selftest plumbing with CTest.

To use the selftests, build with -DLWS_WITH_MINIMAL_EXAMPLES=1
and `CTEST_OUTPUT_ON_FAILURE=1 make test` or just
`make test`.

To disable tests that require internet access, also give
-DLWS_CTEST_INTERNET_AVAILABLE=0

Remove travis and appveyor scripts on master.

Remove travis and appveyor decals on README.md.

Lws now strips out http headers releated to h2, ws and unusual headers
based on cmake config settings for those features... it saves some heap
for the ah and reduces the table size in .rodata.

It's possible code might have some external dependency on the original
header indexes, but, eg, you don't enable h2 so those indexes are
optimized with the h2 ones taken out.

This introduces a cmake option "LWS_HTTP_HEADERS_ALL", default-OFF, that
defeats the header table optimization for compatibility with older
versions in the case the client software can't be adapted to use the
lws-exported matching header enums.

You probably don't need this.

LWS builds OK on iOS SDK as unix type plat, except it
doesn't have net/route.h.

Detect we're building on iOS at CMake and export a
preprocessor define we can use to snip out the missing
include.

By default this doesn't change any existing logging behaviour at all.

But it allows you to define cmake options to force or force-disable the
build of individual log levels using new cmake option bitfields
LWS_LOGGING_BITFIELD_SET and LWS_LOGGING_BITFIELD_CLEAR.

Eg, -DLWS_LOGGING_BITFIELD_SET="(LLL_INFO)" can force INFO log level
built even in release mode.  -DLWS_LOGGING_BITFIELD_CLEAR="(LLL_NOTICE)"
will likewise remove NOTICE logging from the build regardless of
DEBUG or RELEASE mode.

When libwebsockets is included as a subdirectory in other projects that rely on a minimum CMake version of 3.x, a CMP0048 policy warning will be raised due to the project not specifying a version in the project call.

This patch silences the warning by explicitly setting the policy within libwebsockets to NEW if it has already been forwarded as such, without any further impact on the behavior of CMake.