Fixed issue with Mysql. Sometimes it will throw and exception depending on the version.

git-svn-id: http://svn.igniterealtime.org/svn/repos/openfire/trunk@10641 b35dd754-fafc-0310-a699-88a17e54d16e

src/plugins/packetFilter/src/java/org/jivesoftware/openfire/plugin/rules/DbRuleManager.java

@@ -171,6 +171,8 @@ public class DbRuleManager {
             }
         } catch (SQLException sqle) {
             Log.error(sqle);
+            // Result set probably empty
+            return 0;
         }
         finally {
             DbConnectionManager.closeConnection(pstmt, con);