Update the nlm_cmp_addr() helper to support AF_INET6 as well as AF_INET
addresses.  New version takes two "struct sockaddr *" arguments instead of
"struct sockaddr_in *" arguments.
Signed-off-by: NChuck Lever <chuck.lever@oracle.com>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>