try to fix tests on windows where the "file not found" error is different from linux

Author: matthiaskrgr

tests/ui/unpretty/staged-api-invalid-path-108697.rs

@@ -2,7 +2,7 @@
 // ICE: tcx.resolutions(()) is not supported for local crate -Zunpretty=mir
 // on invalid module path with staged_api
 //@ compile-flags: -Zunpretty=mir
-
+//@ normalize-stderr-test: "The system cannot find the file specified." -> "No such file or directory"
 #![feature(staged_api)]
 #[path = "lol"]
 mod foo;