THRIFT-3067 C++ cppcheck performance related warnings

Patch: Arijit Chattopadhyay <arijitnit06@gmail.com>

This closes #444
diff --git a/compiler/cpp/src/parse/t_service.h b/compiler/cpp/src/parse/t_service.h
index 091403d..1f49972 100644
--- a/compiler/cpp/src/parse/t_service.h
+++ b/compiler/cpp/src/parse/t_service.h
@@ -39,7 +39,7 @@
 
   void add_function(t_function* func) {
     std::vector<t_function*>::const_iterator iter;
-    for (iter = functions_.begin(); iter != functions_.end(); iter++) {
+    for (iter = functions_.begin(); iter != functions_.end(); ++iter) {
       if (func->get_name() == (*iter)->get_name()) {
         throw "Function " + func->get_name() + " is already defined";
       }