* cygheap.cc (cygheap_fixup_in_child): It's not just for exec.

* cygtls.h (struct _cygtls::thread_handle): New field.
* dcrt0.cc (exit_lock): Remove declaration.
* winsup.h (exit_lock): Add declaration.
* exceptions.cc (sigpacket::process): Properly return after signal_exit.
* pinfo.cc (pinfo::exit): Only exit the process if _my_tls.thread_handle has
not been filled out -- which should be an impossible event.
* sigproc.cc (sigproc_terminate): Fillout _my_tls.thread_handle to provide
something for wait_sig to wait for.  Use the siginfo_t version of sig_send and
fill out the tls argument with _my_tls.
(wait_sig): Wait for the thread specified in pack.tls or (for now) complain
bitterly if it doesn't exit.

winsup/cygwin/exceptions.cc

@@ -1162,6 +1162,7 @@ exit_sig:
   sigproc_printf ("signal %d, about to call do_exit", si.si_signo);
   signal_exit (si.si_signo);
   /* May not return */
+  return rc;
 }
 
 CRITICAL_SECTION NO_COPY exit_lock;