aklog: Search for /etc/krb5/krb5.conf

aklog tweaks the KRB5_CONFIG environment var when performing one of
our 'weak crypto' workarounds. We assume that the default krb5.conf is
/etc/krb5.conf, but for Solaris 11 libkrb5, krb5.conf is in
/etc/krb5/krb5.conf. Although this file could be anywhere, try
/etc/krb5/krb5.conf too, so we at least work on stock Solaris.

Change-Id: I1f53b9b58549da04f2a27f1f579dd0084796e51d
Reviewed-on: http://gerrit.openafs.org/9666
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>