fix incremental tests

src/test/incremental/warnings-reemitted.rs

@@ -2,8 +2,8 @@
 // compile-flags: -Coverflow-checks=on
 // build-pass (FIXME(62277): could be check-pass?)
 
-#![warn(const_err)]
+#![warn(overflow)]
 
 fn main() {
-    let _ = 255u8 + 1; //~ WARNING attempt to add with overflow
+    let _ = 255u8 + 1; //~ WARNING operation will overflow
 }