glsl2: Use ir_dead_code's linked version after linking.
glsl-fs-raytrace-bug27060 goes from 485 Mesa IR instructions to 389
before Mesa IR optimization.
diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index ea0274e..06f2a82 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1262,9 +1262,7 @@
progress = do_if_simplification(ir) || progress;
progress = do_copy_propagation(ir) || progress;
progress = do_dead_code_local(ir) || progress;
-#if 0
- progress = do_dead_code_unlinked(state, ir) || progress;
-#endif
+ progress = do_dead_code_unlinked(ir) || progress;
progress = do_constant_variable_unlinked(ir) || progress;
progress = do_constant_folding(ir) || progress;
progress = do_if_return(ir) || progress;