return 0 from Client.available() when Client is invalid (same as stock Ethernet-lib)

ntruchsess · ntruchsess · commit 6832d8ab64db · 2014-01-15T00:11:42.000+01:00
diff --git a/UIPClient.cpp b/UIPClient.cpp
@@ -212,7 +212,7 @@ UIPClient::available()
 {
   if (*this)
     return _available(data);
-  return -1;
+  return 0;
 }
 
 int
