gen6_mfc build fail

[Zenitur]

Hello. I'm using Debian 8 with the self-upgraded libva2 1.17 with the DRI3 disabled. GCC 4.9, LLVM 7.0. This is a build error.

make[3]: Entering directory '/home/desktop/intel-vaapi-driver-master/src'
/bin/bash ../libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H -I.  -DPTHREADS -I/usr/include/libdrm   -DVA_DRIVERS_PATH="\"/usr/lib/x86_64-linux-gnu/dri\""   -Wall -fvisibility=hidden  -fstack-protector  -g -O2 -fstack-protector -c -o libi965_drv_video_la-gen6_mfc.lo `test -f 'gen6_mfc.c' || echo './'`gen6_mfc.c
libtool: compile:  gcc -DHAVE_CONFIG_H -I. -DPTHREADS -I/usr/include/libdrm -DVA_DRIVERS_PATH=\"/usr/lib/x86_64-linux-gnu/dri\" -Wall -fvisibility=hidden -fstack-protector -g -O2 -fstack-protector -c gen6_mfc.c  -fPIC -DPIC -o .libs/libi965_drv_video_la-gen6_mfc.o
In file included from intel_driver.h:16:0,
                 from intel_batchbuffer.h:9,
                 from gen6_mfc.c:35:
intel_compiler.h:55:22: error: missing binary operator before token "("
 #elif __has_attribute(fallthrough)
                      ^
Makefile:886: recipe for target 'libi965_drv_video_la-gen6_mfc.lo' failed
make[3]: *** [libi965_drv_video_la-gen6_mfc.lo] Error 1
make[3]: Leaving directory '/home/desktop/intel-vaapi-driver-master/src'
Makefile:1419: recipe for target 'all-recursive' failed
make[2]: *** [all-recursive] Error 1
make[2]: Leaving directory '/home/desktop/intel-vaapi-driver-master/src'
Makefile:667: recipe for target 'all' failed
make[1]: *** [all] Error 2
make[1]: Leaving directory '/home/desktop/intel-vaapi-driver-master/src'
Makefile:401: recipe for target 'all-recursive' failed
make: *** [all-recursive] Error 1

[Zenitur]

The commit that breaks the build: 3fa8045

[irql-notlessorequal]

Typically with such old setups I would close the issue considering that the last GCC 4.x series release was over ten years ago, I'm deciding to make an exception and will fix this.

The linked PR should fix this.