url: initialize speed-check data for file:// protocol

... in order to prevent an artificial timeout event based on stale
speed-check data from a previous network transfer.  This commit fixes
a regression caused by 9dd85bced5.

Bug: https://bugzilla.redhat.com/906031

lib/url.c

@@ -5193,6 +5193,9 @@ static CURLcode create_conn(struct SessionHandle *data,
                           -1, NULL); /* no upload */
     }
 
+    /* since we skip do_init() */
+    Curl_speedinit(data);
+
     return result;
   }
 #endif