THRIFT-3067 C++ cppcheck performance related warnings

Patch: Arijit Chattopadhyay <arijitnit06@gmail.com>

This closes #444
diff --git a/contrib/fb303/cpp/FacebookBase.cpp b/contrib/fb303/cpp/FacebookBase.cpp
index 8003340..3c56975 100644
--- a/contrib/fb303/cpp/FacebookBase.cpp
+++ b/contrib/fb303/cpp/FacebookBase.cpp
@@ -98,7 +98,7 @@
   // want our read/write structure to go over the wire
   counters_.acquireRead();
   for(ReadWriteCounterMap::iterator it = counters_.begin();
-      it != counters_.end(); it++)
+      it != counters_.end(); ++it)
   {
     _return[it->first] = it->second.value;
   }