Add krb5_enomem for config parser & kernel crypto

The imported code form Heimdal that forms our config file parser
and kernel rfc3961 library now makes use of krb5_enomem. Provide
an implementation so we build again ...

Change-Id: Ie7162d73aa97e6f7594c0e7c68ed6939f57ae884
Reviewed-on: http://gerrit.openafs.org/9265
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>