Fix #3497: Add support for compiling in g++ 4.4 and 4.5

- Removed uses of lambda expressions

- Added custom defines for constexpr and nullptr

- Removed trailing comma of last value from generated enums

src/flatc.cpp

@@ -17,6 +17,7 @@
 #include "flatbuffers/flatbuffers.h"
 #include "flatbuffers/idl.h"
 #include "flatbuffers/util.h"
+#include <limits>
 
 static void Error(const std::string &err, bool usage = false,
                   bool show_exe_name = true);