Cygwin: console: Make suspending process work properly.

- After commit f4b47827cf, suspending
  process by Ctrl-Z does not work in console and results in hang up.
  This patch fixes the issue.

winsup/cygwin/fhandler_console.cc

@@ -850,7 +850,9 @@ fhandler_console::process_input_message (void)
       if (toadd)
 	{
 	  ssize_t ret;
+	  release_input_mutex ();
 	  line_edit_status res = line_edit (toadd, nread, *ti, &ret);
+	  acquire_input_mutex (INFINITE);
 	  if (res == line_edit_signalled)
 	    {
 	      stat = input_signalled;