* exceptions.cc (setup_handler): Signal event for any sigwaitinfo if it exists

* exceptions.cc (setup_handler): Signal event for any sigwaitinfo if it exists
to force signal to be handled.  Zero event here to prevent races.
* signal.cc (sigwaitinfo): Use local handle value for everything since signal
thread could zero event element at any time.  Detect when awaking due to thread
not in mask and set return value and errno accordingly.  Don't set signal
number to zero unless we've recognized the signal.
* sigproc.cc (sigq): Rename from sigqueue throughout.
* thread.cc (pthread::join): Handle signals received while waiting for thread
to terminate.
* cygwin.din: Export sighold, sigqueue.
* exceptions.cc (sighold): Define new function.
* signal.cc (handle_sigprocmask): Set correct errno for invalid signal.
Simplify debugging output.
(sigqueue): Define new function.
* include/cygwin/signal.h (sighold): Declare new function.
(sigqueue): Ditto.
* include/cygwin/version.h: Bump API minor version number.
* include/limits.h (TIMER_MAX): Define.
(_POSIX_TIMER_MAX): Ditto.