glx: fix Scons build
glx: fix Scons build

Replace -h with --header-tag as was done for the Makefile build.

Reviewed-by: Dylan Baker <91de990240e6abc00928035c476e6ad54ab72b92@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler