Consolidate start/finish of monitor on different platforms into

one API. Monitor is started either before main loop, if scanner
isn't running, or in the main loop once we finished waiting for
the scanner.

monitor.h

@@ -7,13 +7,6 @@ int monitor_remove_directory(int fd, const char * path);
 #define	HAVE_WATCH 1
 int	monitor_add_watch(int, const char *);
 int	monitor_remove_watch(int, const char *);
-#endif
-
-#ifdef HAVE_INOTIFY
-void *
-start_inotify();
-#endif
-
-#ifdef HAVE_KQUEUE
-void	kqueue_monitor_start();
+void 	monitor_start();
+void 	monitor_stop();
 #endif