glsl: Add compute to _mesa_shader_stage_to_string(); use unreachable.
glsl: Add compute to _mesa_shader_stage_to_string(); use unreachable.

This is basically Ian's review feedback for my patch that added
_mesa_shader_stage_to_abbrev() - it just makes both consistent again.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler