[add error log for flock]

src/dnode/src/dnodeMain.c

@@ -159,7 +159,7 @@ static void dnodeCheckDataDirOpenned(char *dir) {
   }
   int32_t ret = flock(fd, LOCK_EX | LOCK_NB);
   if (ret != 0) {
-    dError("failed to lock file:%s ret:%d, database may be running, quit", filepath, ret);
+    dError("failed to lock file:%s ret:%d[%s], database may be running, quit", filepath, ret, strerror(errno));
     close(fd);
     exit(0);
   }