obfsproxy: Wrong sizeof target in pending_socks_cb()

network.c:pending_socks_cb()

...
    struct sockaddr_storage ss;
    struct sockaddr *sa = (struct sockaddr*)&ss;
    socklen_t slen = sizeof(&ss);
...
    if (getpeername(bufferevent_getfd(bev), sa, &slen) == 0) {
...

slen gets filled with the size of the pointer, but we want it to be filled with the size of sockaddr.