xmesa: do not wrap header inclusion in extern "C"
xmesa: do not wrap header inclusion in extern "C"

Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler