fixes #1430 nng_sockaddr larger than nng_sockaddr_storage
fixes #1430 nng_sockaddr larger than nng_sockaddr_storage

This bug can easily lead to memory overruns if a program relies
on the nng_sockaddr_storage instad of just allocating a vanilla
nng_sockaddr.

nanomsg/nng,nanomsg/nng,nanomsg/nng,nanomsg/nng