mesa: fix up GLSL version when computing GL version
mesa: fix up GLSL version when computing GL version

In some situations it is convenient for a driver to expose a higher GLSL
version while some extensions are still incomplete. However in that
situation, it would report a GLSL version that was higher than the GL
version. Avoid that situation by limiting the GLSL version to the GL
version.

Signed-off-by: Ilia Mirkin <bcbbb7aa705ec3a5fc5824c01a845186c3d62fca@alum.mit.edu>
Reviewed-by: Brian Paul <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@vmware.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler