exchanged code containing goto with a do while loop (#1758)

exchanged code containing goto with a do while loop

lightningd/watch.c

@@ -270,8 +270,7 @@ void watch_topology_changed(struct chain_topology *topo)
 	struct txwatch_hash_iter i;
 	struct txwatch *w;
 	bool needs_rerun;
-
+	do {
-again:
 		/* Iterating a htable during deletes is safe, but might skip entries. */
 		needs_rerun = false;
 		for (w = txwatch_hash_first(&topo->txwatches, &i);
@@ -283,6 +282,5 @@ again:
 			if (depth)
 				needs_rerun |= txw_fire(w, &w->txid, depth);
 		}
-	if (needs_rerun)
+	} while (needs_rerun);
-		goto again;
 }