gitlab-ci: simplify $CROSS option

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
14 jobs for !1634 with gitlab-ci-simplify-cross in 10 seconds (queued for 2 seconds)
detached
Status Name Job ID Coverage
  Containers Build
canceled debian #493764

00:00:10

 
  Build+Test
skipped meson-arm64 #493773
skipped meson-armhf #493772
skipped meson-clang #493766
skipped meson-clover #493770
skipped meson-i386 #493774
skipped meson-main #493769
skipped meson-swr-glvnd #493765
skipped meson-vulkan #493771
skipped scons-llvm #493776
skipped scons-nollvm #493775
skipped scons-swr #493767
skipped scons-win64 #493768
 
  External
canceled continuous-integration/appveyor/branch