mesa: Free the util shaders with the gallium's FREE.

src/mesa/state_tracker/st_atom_shader.c

@@ -313,7 +313,7 @@ get_passthrough_fs(struct st_context *st)
       st->passthrough_fs =
          util_make_fragment_passthrough_shader(st->pipe, &shader);
 #if 0      /* We actually need to keep the tokens around at this time */
-      _mesa_free((void *) shader.tokens);
+      util_free_shader(&shader);
 #endif
    }