qemu: move build outside of kernel dir to avoid kernel's make clean

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

.gitignore

 cscope.out
 *.o
+*.d
 *.ko
 *.mod.c
+src/tools/wg
 Module.symvers
 *.cmd
 .tmp_versions
@@ -9,3 +11,11 @@ Module.symvers
 modules.order
 modules.builtin
 maint/
+qemu-build/
+src/tests/qemu/distfiles/
+*.id0
+*.id1
+*.id2
+*.nam
+*.til
+*.pro.user

src/tests/qemu/.gitignore

-build/
-distfiles/

src/tests/qemu/Makefile

@@ -2,7 +2,7 @@ PWD := $(shell pwd)
 
 # Set these from the environment to override
 KERNEL_VERSION ?= 4.8.6
-BUILD_PATH ?= $(PWD)/build
+BUILD_PATH ?= $(PWD)/../../../qemu-build
 DISTFILES_PATH ?= $(PWD)/distfiles
 DEBUG_KERNEL ?= no
 NR_CPUS ?= 2