socket-util: introduce port argument in sockaddr_port()

socket-util: introduce port argument in sockaddr_port()

sockaddr_port() either returns a >= 0 port number or a negative errno.
This works for AF_INET and AF_INET6 because port ranges are only 16-bit.

In AF_VSOCK ports are 32-bit so an int cannot represent all port number
and negative errnos.  Separate the port and the return code.