* child_info.h (child_info::postfork): Define new function.

* fork.cc (frok::parent): Call postfork to do all of the manipulation required
prior to calling pinfo::remember.
* pinfo.h (pinfo::set_rd_proc_pipe): Just set pinfo's rd_proc_pipe.  Don't
bother setting it to NULL.
* sigproc.cc (child_info_spawn::wait_for_myself): Call postfork to set up
myself for waiting.
* spawn.cc (child_info_spawn::worker): Avoid now-unnecessary global lock.
Consistently test mode rather than chtype when making wr_proc_pipe decisions.
Call postfork() to set up stuff prior to pinfo::remember.

winsup/cygwin/pinfo.h

@@ -139,7 +139,7 @@ public:
   HANDLE hProcess;
   HANDLE rd_proc_pipe;
   pinfo_minimal (): h (NULL), hProcess (NULL), rd_proc_pipe (NULL) {}
-  void set_rd_proc_pipe (HANDLE& h) {rd_proc_pipe = h; h = NULL;}
+  void set_rd_proc_pipe (HANDLE& h) {rd_proc_pipe = h;}
   friend class pinfo;
 };