Do not rely on exact error code.

cjgillot · cjgillot · commit 7e214bfc8a55 · 2023-04-21T16:14:44.000Z
diff --git a/tests/run-make/const-prop-lint/Makefile b/tests/run-make/const-prop-lint/Makefile
@@ -6,4 +6,4 @@ include ../tools.mk
 
 all:
 	$(RUSTC) input.rs; test $$? -eq 1
-	ls *.o; test $$? -eq 2
+	ls *.o; test $$? -ne 0
