This change list allows a user to override the GLSL version from the
command line or through the C and C++ interfaces. This will override the
override happens in ProcessDeferred() before DeduceVersionProfile() so
the process should still error out if the version is insufficient for
the shader code.
- Added --glsl-version <version> to CLI.
- Added parameter to route glslVersion as override version to
preprocessor and parse functions to C++ interface.
- Updated C interface with function to override GLSL version.