* cygthread.cc (cygthread::detach): Make error message a little more detailed.

* fhandler.cc (fhandler_base::raw_read): Ditto for debug message.
* dcrt0.cc (do_exit): Add some more synchronization tests.
* fhandler_fifo.cc (fhandler_fifo::dup): Don't duplicate a nonexistent handle.
Use derived return value rather than always retuning 0.
* fhandler_netdrive.cc (fhandler_netdrive::exists): Wnet -> WNet.
* winsup.h (exit_states): Add a couple of new exit states.

winsup/cygwin/dcrt0.cc

@@ -1013,8 +1013,18 @@ do_exit (int status)
 #endif
 
   EnterCriticalSection (&exit_lock);
-  muto::set_exiting_thread ();
-  dll_global_dtors ();
+
+  if (exit_state < ES_SET_MUTO)
+    {
+      exit_state = ES_SET_MUTO;
+      muto::set_exiting_thread ();
+    }
+
+  if (exit_state < ES_GLOBAL_DTORS)
+    {
+      exit_state = ES_GLOBAL_DTORS;
+      dll_global_dtors ();
+    }
 
   if (exit_state < ES_EVENTS_TERMINATE)
     {