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/pinfo.h

@@ -196,10 +196,9 @@ public:
     destroy = res ? false : true;
     return res;
   }
-  int remember (bool detach)
+  int remember ()
   {
-    int res = proc_subproc (detach ? PROC_DETACHED_CHILD : PROC_ADD_CHILD,
-			    (uintptr_t) this);
+    int res = proc_subproc (PROC_ADD_CHILD, (uintptr_t) this);
     destroy = res ? false : true;
     return res;
   }