mesa: add new program optimizer code

This is pretty simplistic for now, but helps with certain shaders.

src/mesa/SConscript

@@ -193,6 +193,7 @@ if env['platform'] != 'winddk':
 		'shader/prog_execute.c',
 		'shader/prog_instruction.c',
 		'shader/prog_noise.c',
+		'shader/prog_optimize.c',
 		'shader/prog_parameter.c',
 		'shader/prog_print.c',
 		'shader/prog_statevars.c',