Fix test_compiler_*_stds tests after last commit
Fix test_compiler_*_stds tests after last commit

Since sanity check now includes CFLAGS, the test fails earlier.

But if the compiler is ICC, it will only fail during the build proper as
before, since that's where where the flag making `-std=unknown` an error
not warning is used.

mesonbuild/meson,mesonbuild/meson,jpakkane/meson,becm/meson,becm/meson,jpakkane/meson,pexip/meson,becm/meson,jpakkane/meson,pexip/meson,QuLogic/meson,pexip/meson,QuLogic/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,QuLogic/meson,QuLogic/meson,becm/meson,pexip/meson,jpakkane/meson,becm/meson,jpakkane/meson,pexip/meson,becm/meson,mesonbuild/meson,pexip/meson,becm/meson,jpakkane/meson,jpakkane/meson,mesonbuild/meson,QuLogic/meson,jpakkane/meson,mesonbuild/meson,becm/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,becm/meson,mesonbuild/meson,becm/meson,QuLogic/meson,QuLogic/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson