watcher: properly break out in nested blocks

Found via staticcheck:

watcher.go:48:5: ineffective break statement. Did you mean to break out of the outer loop? (SA4011)

watcher.go

@@ -45,7 +45,7 @@ func WatchForUpdates(filename string, done <-chan bool, action func()) {
 			select {
 			case _ = <-done:
 				log.Printf("Shutting down watcher for: %s", filename)
-				break
+				return
 			case event := <-watcher.Events:
 				// On Arch Linux, it appears Chmod events precede Remove events,
 				// which causes a race between action() and the coming Remove event.