* nscd/nscd.h (struct database_dyn): Add inotify_descr and clear_cache

* nscd/nscd.h (struct database_dyn): Add inotify_descr and clear_cache

	fields.
	* nscd/connections.c (inotify_fd): New variable.
	(nscd_init): Try to open an inotify descriptor.
	If successful, watch files for databases using inotify instead of
	having prune threads stat the files.
	(nscd_run_prune): Recognize clear_cache flag being set and call
	prune_cache appropriately.
	(main_loop_poll): Add inotify descriptor to wait set and handle the
	reported changes.
	(main_loop_epoll): Likewise.
	* nscd/cache.c (prune_cache): Don't stat files for databases if
	inotify is used.
	* sysdeps/unix/sysv/linux/Makefile [subdir=nscd]
	(CFLAGS-connections.c): Add -DHAVE_INOTIFY.