socketmodule: FreeBSD PF_DIVERT is missing in getsockaddrlen()

glebius

from socket import socket, PF_DIVERT, SOCK_RAW
with socket(PF_DIVERT, SOCK_RAW, 0) as fd:
        r = fd.recvfrom(16384)

The above fails, while must work. This is my miss with submission #96536. Opening pull request shortly.