test_librbd_fsx: sleep before exit

This gives the log time to flush to disk.  Kludgey!

Signed-off-by: Sage Weil <sage@inktank.com>

src/test/rbd/fsx.c

@@ -400,6 +400,7 @@ report_failure(int status)
 		}
 		close(fsxgoodfd);
 	}
+	sleep(3);   // so the log can flush to disk.  KLUDGEY!
 	exit(status);
 }