Testsuite: fix normalisation for unlit

T8430 shows:
  `js-unknown-ghcjs-unlit' failed in phase `Literate pre-processor'. (Exit code: 1)

Notice the quote around the program name. So I've made the regex match
more cases (i.e. not only lines starting with the program name).

testsuite/driver/testlib.py

@@ -2313,7 +2313,7 @@ def normalise_errmsg(s: str) -> str:
     s = re.sub('ghc-stage[123]', 'ghc', s)
     # Remove platform prefix (e.g. js-unknown-ghcjs) for cross-compiled ghc
     s = re.sub('^\\w+-\\w+-\\w+-ghc', 'ghc', s)
-    s = re.sub('^\\w+-\\w+-\\w+-unlit', 'unlit', s)
+    s = re.sub('\\w+-\\w+-\\w+-unlit', 'unlit', s)
 
     # On windows error messages can mention versioned executables
     s = re.sub('ghc-[0-9.]+', 'ghc', s)