* linux-thread-db.c (set_libthread_db_search_path): New function.

	* linux-thread-db.c (set_libthread_db_search_path): New function.
	(_initialize_thread_db): Add setter for libthread-db-search-path.

	gdbserver/
	* thread-db.c (thread_db_handle_monitor_command): Handle elided path.

	doc/
	* gdb.texinfo (Threads): If an empty path is provided for
	libthread-db-search-path it is reset to its default value.
	(Server): Ditto.