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/cmd.go

@@ -17,6 +17,7 @@ import (
 	"runtime/pprof"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/pkg/errors"
@@ -293,7 +294,7 @@ func ShowStats() bool {
 // Run the function with stats and retries if required
 func Run(Retry bool, showStats bool, cmd *cobra.Command, f func() error) {
 	var err error
-	var stopStats chan struct{}
+	stopStats := func() {}
 	if !showStats && ShowStats() {
 		showStats = true
 	}
@@ -331,9 +332,7 @@ func Run(Retry bool, showStats bool, cmd *cobra.Command, f func() error) {
 			time.Sleep(*retriesInterval)
 		}
 	}
-	if showStats {
-		close(stopStats)
-	}
+	stopStats()
 	if err != nil {
 		log.Printf("Failed to %s: %v", cmd.Name(), err)
 		resolveExitCode(err)
@@ -384,24 +383,31 @@ func CheckArgs(MinArgs, MaxArgs int, cmd *cobra.Command, args []string) {
 
 // StartStats prints the stats every statsInterval
 //
-// It returns a channel which should be closed to stop the stats.
-func StartStats() chan struct{} {
-	stopStats := make(chan struct{})
-	if *statsInterval > 0 {
-		go func() {
-			ticker := time.NewTicker(*statsInterval)
-			for {
-				select {
-				case <-ticker.C:
-					accounting.Stats.Log()
-				case <-stopStats:
-					ticker.Stop()
-					return
-				}
-			}
-		}()
+// It returns a func which should be called to stop the stats.
+func StartStats() func() {
+	if *statsInterval <= 0 {
+		return func() {}
+	}
+	stopStats := make(chan struct{})
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		ticker := time.NewTicker(*statsInterval)
+		for {
+			select {
+			case <-ticker.C:
+				accounting.Stats.Log()
+			case <-stopStats:
+				ticker.Stop()
+				return
+			}
+		}
+	}()
+	return func() {
+		close(stopStats)
+		wg.Wait()
 	}
-	return stopStats
 }
 
 // initConfig is run by cobra after initialising the flags