* 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.cc

@@ -125,23 +125,6 @@ signal_fixup_after_exec ()
     }
 }
 
-/* Determine if the parent process is alive.
- */
-
-bool __stdcall
-my_parent_is_alive ()
-{
-  bool res;
-  if (myself->cygstarted)
-    res = pid_exists (myself->ppid);
-  else
-    {
-      debug_printf ("Not started by cygwin app");
-      res = false;
-    }
-  return res;
-}
-
 void __stdcall
 wait_for_sigthread ()
 {