Handle broadcast() errors in sendTX()

Replace this.pool.broadcast(tx) with this.broadcast(tx) in case of a
selfish node because the latter handles broadcast errors, whereas the
former does not.

lib/node/fullnode.js

@@ -317,7 +317,7 @@ class FullNode extends Node {
     // We need to announce by hand if
     // we're running in selfish mode.
     if (this.pool.options.selfish)
-      this.pool.broadcast(tx);
+      this.broadcast(tx);
   }
 
   /**