* child_info.h (child_info_fork::parent_wr_proc_pipe): New element.

* fork.cc (fork_parent): Set parent_wr_proc.
* pinfo.cc (set_myself): Close child_proc_info->parent_wr_proc if it exists
rather than trying to get value from parent _pinfo.
* pinfo.h (enum parent_aleter): New enum.
(pinfo::alert_parent): Declare as returning a value.
(pinfo::parent_alive): New function.
* pinfo.cc (pinfo::alert_parent): Set wr_proc_pipe to invalid non-NULL value
when parent disappears.  Return success of operation.
(proc_waiter): Use __ALERT_* enum for control since these are not really
signals.  Implement __ALERT_ALIVE.
* sigproc.cc (my_parent_is_alive): Eliminate.
* sigproc.h (my_parent_is_alive): Ditto for declaration.
(__SIGREPARENT): Eliminate.

winsup/cygwin/sigproc.h

@@ -22,8 +22,7 @@ enum
   __SIGDELETE	    = -(NSIG + 5),
   __SIGFLUSHFAST    = -(NSIG + 6),
   __SIGHOLD	    = -(NSIG + 7),
-  __SIGNOHOLD	    = -(NSIG + 8),
-  __SIGREPARENT	    = (NSIG + 2)
+  __SIGNOHOLD	    = -(NSIG + 8)
 };
 #endif
 
@@ -55,7 +54,6 @@ struct sigpacket
 extern HANDLE signal_arrived;
 extern HANDLE sigCONT;
 
-bool __stdcall my_parent_is_alive ();
 void __stdcall sig_dispatch_pending (bool fast = false);
 #ifdef _PINFO_H
 extern "C" void __stdcall set_signal_mask (sigset_t newmask, sigset_t = myself->getsigmask ());