net/xmlrpc-c: unbreak build with Clang 6 (C++14 by default)

server_abyss.cpp:88:14: error: assigning to 'int' from incompatible type '__bind<int &, sockaddr *,

unsigned long>'
  rc = bind(this->fd, (struct sockaddr *)&sockAddr, sizeof(sockAddr));
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reported by: antoine (via bug 224669)