Skeletons should use virtual inheritance from the interface base


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@664856 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/compiler/cpp/src/generate/t_cpp_generator.cc b/compiler/cpp/src/generate/t_cpp_generator.cc
index c59112c..edf711a 100644
--- a/compiler/cpp/src/generate/t_cpp_generator.cc
+++ b/compiler/cpp/src/generate/t_cpp_generator.cc
@@ -1210,7 +1210,7 @@
   }
 
   f_skeleton <<
-    "class " << svcname << "Handler : public " << svcname << "If {" << endl <<
+    "class " << svcname << "Handler : virtual public " << svcname << "If {" << endl <<
     " public:" << endl;
   indent_up();
   f_skeleton <<