THRIFT-3152 Compiler error on Mac OSX (missing #include <cstdlib>)

Patch: Mathias Gottschlag
diff --git a/lib/cpp/src/thrift/transport/TBufferTransports.h b/lib/cpp/src/thrift/transport/TBufferTransports.h
index eb08d62..98e8a9e 100644
--- a/lib/cpp/src/thrift/transport/TBufferTransports.h
+++ b/lib/cpp/src/thrift/transport/TBufferTransports.h
@@ -20,6 +20,7 @@
 #ifndef _THRIFT_TRANSPORT_TBUFFERTRANSPORTS_H_
 #define _THRIFT_TRANSPORT_TBUFFERTRANSPORTS_H_ 1
 
+#include <cstdlib>
 #include <cstring>
 #include <limits>
 #include <boost/scoped_array.hpp>