Do not call afs_MarinerLog when afs_mariner is not set

When mariner log is not set up (afs_mariner=0), do not call afs_MarinerLog,
otherwise a osi_NetSend() to hostaddress=0 is tried, which will give you
ICMP messages in the socket error queue.
Do not call afs_AddMarinerName, when afs_mariner is not set.

(cherry picked from commit 41f8d6b9239d8ee1ca786c0485bea4251c96b9e5)

Change-Id: Id9584b07a0d3726fdd2176ac04945f976255e2d4
Reviewed-on: http://gerrit.openafs.org/8801
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>