Should fix MSVC link failure.
bool do_vec_index_to_cond_assign(exec_list *instructions);
bool do_vec_index_to_swizzle(exec_list *instructions);
bool lower_discard(exec_list *instructions);
-bool lower_discard_flow(exec_list *instructions);
+void lower_discard_flow(exec_list *instructions);
bool lower_instructions(exec_list *instructions, unsigned what_to_lower);
bool lower_noise(exec_list *instructions);
bool lower_variable_index_to_cond_assign(exec_list *instructions,