X wcfs: Don't noise ZWatcher trace logs with "select ..."

Its just a debugging print - helpful to debug zwatcher, but not helpful
to understand which events the system was observing.

wcfs/wcfs.go

@@ -757,10 +757,15 @@ func (head *Head) zheadUnlock()  { head.zheadMu.Unlock() }
 // -------- 4) ZODB invalidation -> OS cache --------
 
 func traceZWatch(format string, argv ...interface{}) {
-	if !log.V(1) {	// XXX -> 2?
+	if !log.V(1) {
+		return
+	}
+	log.InfoDepth(1, fmt.Sprintf("zwatcher: " + format, argv...))
+}
+func debugZWatch(format string, argv ...interface{}) {
+	if !log.V(2) {
 		return
 	}
-
 	log.InfoDepth(1, fmt.Sprintf("zwatcher: " + format, argv...))
 }
 
@@ -775,7 +780,7 @@ func (root *Root) zwatcher(ctx context.Context, zwatchq chan zodb.Event) (err er
 	var ok bool
 
 	for {
-		traceZWatch("select ...")
+		debugZWatch("select ...")
 		select {
 		case <-ctx.Done():
 			traceZWatch("cancel")