build: Remove unused AX_CHECK_COMPILE_FLAG macro
build: Remove unused AX_CHECK_COMPILE_FLAG macro

Unused since 1a6ae840413d7fb6d2e83f6a83081d5246c7ac9e

Signed-off-by: Andreas Boll <041cac00e0cb793452cecf5c52a77db13d069cf3@gmail.com>
Reviewed-by: Eric Engestrom <de0b63cf2dfb1fae8ed3c3b4244856a05677d4f0@imgtec.com>
Reviewed-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler