the signal number now, as required by POSIX. The latter should just
return 0 on success. Fixes a mysql problem reported by Kurt Schreiner.
-document the new behavior of sigwaitinfo and sigtimedwait
-retain non-POSIX behavior for NetBSD-5 binary compatibility -- the fix
would likely not be polled into the .0-branches, and having 5.0.x and
5.x behave differently would be confusing. Besides that, it was
documented in the manpage all the time.