Cygwin: console: Align the behaviour against signal with pty.

- Currently, read() returns -1 with EINTR if the process is suspended
  by Ctrl-Z and resumed by fg command, while pty continues to read.
  For example, xxd command stops with error "Interrupted system call"
  after Ctrl-Z and fg. This patch aligns the behaviour with pty (and
  Linux).

winsup/cygwin/fhandler_console.cc

@@ -587,7 +587,8 @@ wait_retry:
 	  break;
 	case input_signalled: /* signalled */
 	  release_input_mutex ();
-	  goto sig_exit;
+	  /* The signal will be handled by cygwait() above. */
+	  continue;
 	case input_winch:
 	  release_input_mutex ();
 	  continue;