THRIFT-3067 C++ cppcheck performance related warnings

Patch: Arijit Chattopadhyay <arijitnit06@gmail.com>

This closes #444
diff --git a/contrib/fb303/cpp/ServiceTracker.cpp b/contrib/fb303/cpp/ServiceTracker.cpp
index 2914ff6..7a61b21 100644
--- a/contrib/fb303/cpp/ServiceTracker.cpp
+++ b/contrib/fb303/cpp/ServiceTracker.cpp
@@ -251,7 +251,7 @@
   uint64_t count;
   for (iter = checkpointServiceDuration_.begin();
        iter != checkpointServiceDuration_.end();
-       iter++) {
+       ++iter) {
     count = iter->second.first;
     handler_->setCounter(string("checkpoint_count_") + iter->first, count);
     if (count == 0) {