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/mountlib/mount.go

@@ -226,8 +226,7 @@ be copied to the vfs cache before opening with --vfs-cache-mode full.
 
 			// Show stats if the user has specifically requested them
 			if cmd.ShowStats() {
-				stopStats := cmd.StartStats()
-				defer close(stopStats)
+				defer cmd.StartStats()()
 			}
 
 			// Skip checkMountEmpty if --allow-non-empty flag is used or if