TST: bind bsd socket to loopback instead of all interfaces

[minrk]

Problem:

on macOS, at least, INADDR_ANY is not a connectable host, leading to EHOSTUNREACH when the address is passed to sendto:

tests/test_zmq_poll_fd.cpp:42:test_poll_fd:FAIL: sendto ( send_socket, buf, 10, 0, (struct sockaddr *) &saddr, sizeof (saddr)) failed, errno = 65 (Host unreachable)

Solution

use INADDR_LOOPBACK instead