auth: plug auth realms memory leaks

auth: plug auth realms memory leaks

The function _afsconf_FreeRealms, called by afsconf_CloseInternal, leaks
two afsconf_realms structures.

The function _afsconf_LoadRealms also leaks those two structures when it
fails.

These memory leaks were discovered with valgrind.

Change-Id: I1436ce21609951bc3433b6c91221cc45e78881bc
Reviewed-on: https://gerrit.openafs.org/13395
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>