Don't match on message from exception in symlink test

There apparently are cases where the text in the exception is
localised in the language of the system the tests are running
on, i.e. not necessarily English, in which case this test was
failing.

t/90_symlink.t

@@ -24,7 +24,7 @@ my %Map     = (
     ],
     File::Spec->catfile( $Dir, "linktest_missing_dir.tar" ) => [
         [ 0, qr/SECURE EXTRACT MODE/ ],
-        [ 0, qr/File exists/ ],
+        [ 0, qr/Could not create directory/ ],
     ],
 );