Test the exported strsignal() API, not the (now hidden) internal APInoted by daniel@
Sync with current state of the tree.
Add tests for __strsignal(). Put here since the tests are very similarto the strerror() test.
Try to catch some more errors and adapt to slightly changed strerror.
more tests, okay millert@ (we probably don't pass them all yet, and willafter the strerror_r code is committed).
Add tests for strerror.