run-tests: introduce 'warned' as test result
While running, a test resulting in 'warned' is shown as '~'.
Test results with state warned are listed between the skipped and the failed
tests. Example:
Skipped test-revert-flags.t: missing feature: executable bit
Skipped test-inotify-lookup.t: missing feature: inotify extension support
Warned test-something.t: output changed
Failed test-largefiles.t: output changed
Failed test-subrepo.t: output changed
# Ran 11 tests, 2 skipped, 1 warned, 2 failed.
The test result "warned" will be used in later patches.
[ original upstream message ]