Cygwin: drop PROC_DETACHED_CHILD flag

pinfo::remember with the detach parameter set to true is
the only way to call proc_subproc with PROC_DETACHED_CHILD.
This call is exclusively used in spawn to set up a pinfo for
a detached child, and that pinfo goes out of scope right
afterwards without any further action.

Drop the flag and drop the detach parameter from pinfo::remember.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/fork.cc

@@ -415,7 +415,7 @@ frok::parent (volatile char * volatile stack_here)
      it in afterwards.  This requires more bookkeeping than I like, though,
      so we'll just do it the easy way.  So, terminate any child process if
      we can't actually record the pid in the internal table. */
-  if (!child.remember (false))
+  if (!child.remember ())
     {
       this_errno = EAGAIN;
 #ifdef DEBUGGING0