Work around crashes in X session management after normal shutdown of X server.

Work around crashes in X session management after normal shutdown of X server.

* src/xsmfns.c (x_session_close): New function.
* src/xterm.h: Declare it.

* src/xterm.c (XTread_socket): Don't call x_session_check_input for
  secondary displays.
  (x_term_init): Do not initialize X session management when the initial
  display was a tty frame.
  (x_delete_display): Close X session management when we close its display.

git-archimport-id: lorentey@elte.hu--2004/emacs--multi-tty--0--patch-390