cmd: Fix -P not ending with a new line

Before this fix rclone didn't wait for the stats to be finished before
exiting, so the final new line was never printed.

After this change rclone will wait for the stats routine to cease
before exiting.

cmd/progress.go

@@ -25,8 +25,8 @@ const (
 
 // startProgress starts the progress bar printing
 //
-// It returns a channel which should be closed to stop the stats.
-func startProgress() chan struct{} {
+// It returns a func which should be called to stop the stats.
+func startProgress() func() {
 	stopStats := make(chan struct{})
 	oldLogPrint := fs.LogPrint
 	if !log.Redirected() {
@@ -36,7 +36,10 @@ func startProgress() chan struct{} {
 
 		}
 	}
+	var wg sync.WaitGroup
+	wg.Add(1)
 	go func() {
+		defer wg.Done()
 		progressInterval := defaultProgressInterval
 		if ShowStats() && *statsInterval > 0 {
 			progressInterval = *statsInterval
@@ -54,7 +57,10 @@ func startProgress() chan struct{} {
 			}
 		}
 	}()
-	return stopStats
+	return func() {
+		close(stopStats)
+		wg.Wait()
+	}
 }
 
 // VT100 codes