FBSD: switch afsi_SetServerIPRank implementation

FBSD: switch afsi_SetServerIPRank implementation

Upstream has removed the ia_net{,mask} elements from
struct in_ifaddr, so we can no longer use them directly.
Switch to passing an rx_ifaddr_t (i.e. struct ifaddr*) in instead,
as that uses a slightly different codepath which still works
for our purposes.

We compile the kernel module with -Werror, so storing a pointer
(memcpy return value) in an int is forbidden, hence the conditional
declaration of 't'.

Change-Id: Ifefef88a353f4bd50a714ad88afa3a6f012fa3a1
Reviewed-on: http://gerrit.openafs.org/6203
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>