news/newscache: Fix build with Clang 6

NewsCache.cc:2265:62: error: invalid operands to binary expression ('__bind<int &, sockaddr *, unsigned int>' and 'int')

if (bind(sock, (struct sockaddr *) &nproxy, sizeof(nproxy)) < 0) {
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~

http://beefy11.nyi.freebsd.org/data/head-i386-default/p478276_s338342/logs/errors/newscache-1.2.r.6_4.log