zmq_getsockopt for ZMQ_LAST_ENDPOINT should not return a string with a trailing null byte

106_last_endpoint.t illustrates the problem. There's an extra \0 on the end of the string.

My patch to perl_libzmq3.xs strips the \0 if appropriate. This is a quick and pragmatic fix.

My PAUSE id is MJG.

Thanks for a really useful module!
All the best
Michael