be: Consider 'kills_value' in 'reg_reqs_equal()'.

ir/be/bearch.h

@@ -240,6 +240,7 @@ static inline bool reg_reqs_equal(const arch_register_req_t *req1,
 	    req1->should_be_same    != req2->should_be_same    ||
 	    req1->must_be_different != req2->must_be_different ||
 	    req1->ignore            != req2->ignore            ||
+	    req1->kills_value       != req2->kills_value       ||
 	    (req1->limited != NULL) != (req2->limited != NULL))
 		return false;