mesa: Move the common _mesa_glsl_compile_shader() code to glsl/.

mesa: Move the common _mesa_glsl_compile_shader() code to glsl/.

This code had no relation to ir_to_mesa.cpp, since it was also used by
intel and state_tracker, and most of it was duplicated with the standalone
compiler (which has periodically drifted from the Mesa copy).

v2: Split from the ir_to_mesa to shaderapi.c changes.

Acked-by: Paul Berry <stereotype441@gmail.com> (v1)
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>