Cygwin: pipe, fifo: Call set_no_inheritance() for adjunct handles.

- Currntly, set_no_inheritance() is not called for the adjunct handles
  such as select_sem. This patch fixes the issue.

winsup/cygwin/fhandler.h

@@ -1208,6 +1208,7 @@ public:
   void open_setup (int flags);
   void fixup_after_fork (HANDLE);
   int dup (fhandler_base *child, int);
+  void set_close_on_exec (bool val);
   int close ();
   void __reg3 raw_read (void *ptr, size_t& len);
   int ioctl (unsigned int cmd, void *);

winsup/cygwin/fhandler_fifo.cc

@@ -1817,4 +1817,6 @@ fhandler_fifo::set_close_on_exec (bool val)
 	set_no_inheritance (fc_handler[i].h, val);
       fifo_client_unlock ();
     }
+  if (select_sem)
+    set_no_inheritance (select_sem, val);
 }

winsup/cygwin/fhandler_pipe.cc

@@ -515,6 +515,16 @@ fhandler_pipe_fifo::raw_write (const void *ptr, size_t len)
   return nbytes ?: -1;
 }
 
+void
+fhandler_pipe::set_close_on_exec (bool val)
+{
+  fhandler_base::set_close_on_exec (val);
+  if (read_mtx)
+    set_no_inheritance (read_mtx, val);
+  if (select_sem)
+    set_no_inheritance (select_sem, val);
+}
+
 void
 fhandler_pipe::fixup_after_fork (HANDLE parent)
 {