* fhandler.h (enum conn_state): Add connect_failed state.

* fhandler_socket.cc (fhandler_socket::connect): Set connect_state to
	connect_failed when connect failed.
	* poll.cc (poll): Change errno to EINVAL if allocating memory fails,
	according to SUSv3. Add socket descriptors always to except_fds. Test
	for failed connect and set revents flags appropriately.
	* select.cc (set_bits): Set connect_state to connect_failed when
	select indicates failed nonblocking connect.
	(fhandler_dev_null::select_except): Set except_ready to false so that
	/dev/null is not always in except state.
	(peek_socket): Fix bogus conditional.
	(fhandler_socket::select_write): Treat all connect_states except
	unconnected equivalent to return consistent results.
	(fhandler_windows::select_except): Set except_ready to false so that
	/dev/windows is not always in except state.

winsup/cygwin/fhandler.h

@@ -50,7 +50,8 @@ enum conn_state
 {
   unconnected = 0,
   connect_pending = 1,
-  connected = 2
+  connected = 2,
+  connect_failed = 3
 };
 
 enum line_edit_status