Added null pointer check for C++ separated code.
Added null pointer check for C++ separated code.

juanrubio/msgpack-c,jpetso/msgpack-c,GamePad64/msgpack-c,jpetso/msgpack-c,AALEKH/msgpack-c,soumith/msgpack-c,juanrubio/msgpack-c,soumith/msgpack-c,jonitis/msgpack-c,kern/msgpack-c,GamePad64/msgpack-c,lvfeng1130/msgpack-c,jonitis/msgpack-c,soumith/msgpack-c,kern/msgpack-c,GamePad64/msgpack-c,lvfeng1130/msgpack-c,vashstorm/msgpack-c,lvfeng1130/msgpack-c,juanrubio/msgpack-c,jonitis/msgpack-c,jpetso/msgpack-c,lvfeng1130/msgpack-c,AALEKH/msgpack-c,kern/msgpack-c,vashstorm/msgpack-c,kern/msgpack-c,jpetso/msgpack-c,jen20/msgpack-c,AALEKH/msgpack-c,vashstorm/msgpack-c,vashstorm/msgpack-c,kern/msgpack-c,lvfeng1130/msgpack-c,jen20/msgpack-c,jpetso/msgpack-c,juanrubio/msgpack-c,jen20/msgpack-c,soumith/msgpack-c,soumith/msgpack-c,vashstorm/msgpack-c,jen20/msgpack-c,AALEKH/msgpack-c,jonitis/msgpack-c,AALEKH/msgpack-c,GamePad64/msgpack-c,jonitis/msgpack-c,jen20/msgpack-c,GamePad64/msgpack-c,juanrubio/msgpack-c