Use add/delete_read_fd in xsmfns to simplify. Also restart with initial_argv.

Use add/delete_read_fd in xsmfns to simplify.  Also restart with initial_argv.

* xsmfns.c (ice_connection_closed): Call delete_read_fd.
(x_session_check_input): Change args and return type so it can be used
as argument to add_read_fd.  Make static.  Remove call to select.
Call kbd_buffer_store_event for emacs_event.
(smc_save_yourself_CB): Also store initial argv to SmRestartCommand.
(ice_conn_watch_CB): Call add_read_fd.

* xterm.c (XTread_socket): Remove HAVE_X_SM block with call to
x_session_check_input.
(x_session_initialized): Remove definition.
(x_initialize): Remove setting of x_session_initialized.

* xterm.h (x_session_check_input): Remove declaration.