gitlab-ci: Use the compiler -v output string for $CCACHE_COMPILERCHECK

This should be faster than computing a hash of the compiler binary
contents on each invocation.

v2:
* Don't export & unset CC variable in .meson-cross script (Eric
  Engestrom)

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com> # v1
40 jobs for !2187 with gitlab-ci-ccache-compilercheck in 17 minutes and 19 seconds (queued for 8 seconds)
detached
Status Job ID Name Coverage
  Containers
passed debian-10 #691375

00:00:30

passed debian-9 #691376

00:00:23

passed test-container:arm64 #691377
aarch64

00:00:21

 
  Build
passed meson-arm64 #691380

00:05:37

passed meson-armhf #691379

00:03:51

passed meson-clang #691382

00:08:20

passed meson-clover #691385

00:06:35

passed meson-clover-old-llvm #691386

00:06:17

passed meson-i386 #691388

00:05:04

passed meson-main #691378

00:12:04

passed meson-swr-glvnd #691381

00:07:14

passed meson-vulkan #691387

00:03:13

passed scons #691389

00:09:58

passed scons-old-llvm #691390

00:10:53

passed scons-swr #691383

00:05:47

passed scons-win64 #691384

00:08:19

 
  Test
passed arm64_a306_gles2 1/4 #691411
db410c

00:04:12

passed arm64_a306_gles2 2/4 #691412
db410c

00:05:58

passed arm64_a306_gles2 3/4 #691413
db410c

00:10:05

passed arm64_a306_gles2 4/4 #691414
db410c

00:04:24

passed arm64_a630_gles2 #691400
mesa-cheza

00:04:26

passed arm64_a630_gles31 1/4 #691401
mesa-cheza

00:06:38

passed arm64_a630_gles31 2/4 #691402
mesa-cheza

00:06:40

passed arm64_a630_gles31 3/4 #691403
mesa-cheza

00:07:49

passed arm64_a630_gles31 4/4 #691404
mesa-cheza

00:07:24

passed arm64_a630_gles3 1/6 #691405
mesa-cheza

00:05:01

passed arm64_a630_gles3 2/6 #691406
mesa-cheza

00:04:04

passed arm64_a630_gles3 3/6 #691407
mesa-cheza

00:03:42

passed arm64_a630_gles3 4/6 #691408
mesa-cheza

00:04:18

passed arm64_a630_gles3 5/6 #691409
mesa-cheza

00:04:13

passed arm64_a630_gles3 6/6 #691410
mesa-cheza

00:04:03

passed test-llvmpipe-gles2 1/4 #691391

00:03:32

passed test-llvmpipe-gles2 2/4 #691392

00:04:40

passed test-llvmpipe-gles2 3/4 #691393

00:03:20

passed test-llvmpipe-gles2 4/4 #691394

00:04:07

passed test-softpipe-gles2 1/4 #691395

00:01:34

passed test-softpipe-gles2 2/4 #691396

00:01:43

passed test-softpipe-gles2 3/4 #691397

00:01:33

passed test-softpipe-gles2 4/4 #691398

00:01:28

passed test-softpipe-gles3-limited #691399

00:03:52