* exceptions.cc (sigtid): Remove declaration.

* exceptions.cc (sigtid): Remove declaration.
(handle_exceptions): Use _sig_tls rather than sigtid to determine if this is
the signal thread.
(set_signal_mask): Ditto for conditionalized CGF code.
* pinfo.cc (pinfo::exit): Exit the thread if we forcefully terminated the main
thread
* sigproc.cc (sigtid): Delete.
(_sig_tls): Define.
(sig_clear): Use _sig_tls rather than sigtid to determine if this is the signal
thread.
(sig_dispatch_pending): Ditto.
(wait_sig): Set _sig_tls here.
* dcrt0.cc (do_exit): Move sigproc_terminate call later since signal handling
was still needed for subsequent stuff.  Call sigproc_terminate with new
exit_state value.
* pinfo.cc (pinfo::exit): Call sigproc_terminate with new exit_state value.
* sigproc.cc (proc_terminate): Remove unnecessary (void) parameter.
(sigproc_terminate): Ditto.  Add new argument to accept exit state to be set.
(wait_sig): Reorganize __SIGEXIT handling.  Add more debugging output.
* winsup.h (sigproc_terminate): Declare with new exit_state argument.
(exit_states): Reorganize to reflect new exit ordering of sigproc_terminate.