* pinfo.h (_pinfo::set_exit_state): Declare new function.

(pinfo::exit): Move here from _pinfo::exit.
* sigproc.cc (child_info::sync): Use new function to set exitcode and
process_state.
* pinfo.cc (_pinfo::exit): Ditto.
(proc_waiter): Ditto.
(_pinfo::set_exit_state): Define new function.
(_pinfo::dup_proc_pipe): Close handle when there is no parent process around to
care about the exit value.
* dcrt0.cc (dll_crt0_0): Move subproc_ready synchronization later to make sure
that myself is still mapped in parent.
(do_exit): Reflect movement to pinfo::exit.
(__api_fatal): Ditto.
* exceptions.cc (signal_exit): Ditto.
* errno.cc (errmap): Map PROC_NOT_FOUND.
* init.cc (dll_entry): Release myself before exiting.
* sigproc.cc (proc_can_be_signalled): Set errno appropriately.
(sig_send): Ditto.  Also remove ill-advised test for !myself->sendsig since
this is an indication of a process which is still initializating -- it is not
an error.
(child_info::sync): Don't set exitcode here.  Assume that will happen in
proc_waiter, if necessary.
* spawn.cc (spawn_guts): Delay "wait_for_myself" logic until later.  Don't wait
at all if the process has already exited.  Reflect movement to pinfo::exit.

winsup/cygwin/pinfo.h

@@ -27,6 +27,8 @@ enum picom
 };
 
 #define EXITCODE_UNSET 0x80000000
+#define EXITCODE_NOSET EXITCODE_UNSET
+#define EXITCODE_EXEC EXITCODE_UNSET
 
 class _pinfo
 {
@@ -83,8 +85,6 @@ public:
   HANDLE tothem;
   HANDLE fromthem;
 
-  void exit (UINT n, bool norecord = 0) __attribute__ ((noreturn, regparm(2)));
-
   inline void set_has_pgid_children ()
   {
     if (pgid == pid)
@@ -155,6 +155,8 @@ public:
     if (destroy && procinfo)
       release ();
   }
+  void exit (DWORD n) __attribute__ ((noreturn, regparm(2)));
+  void set_exit_state (DWORD) __attribute__ ((regparm(2)));
   void initialize_lock () {InitializeCriticalSection (&_lock);}
   void lock () {EnterCriticalSection (&_lock);}
   void unlock () {LeaveCriticalSection (&_lock);}