of resources to be killed at sighup or program exit.
(make_lshd_options): Create the resource list, and register it
with the gc.
(pid_file_resource): New class.
(sighup_close_callback): New class.
(do_sighup_close_callback): New SIGHUP handler.
(make_sighup_close_callback): New function.
(close_on_sighup): New command.
(make_lshd_listen): Close listen socket on SIGHUP.
(do_terminate_callback): Always catch SIGTERM.
(install_signal_handlers): Renamed the function
install_terminate_handler. Now installs handlers for both SIGHUP
and SIGTERM.
(main): Arrange for the pidfile to be deleted at exit or SIGHUP.

Rev: src/lshd.c:1.136