com_err: correctly deal with lack of libintl

com_err: correctly deal with lack of libintl

On machines lacking a libintl, _intlize() currently fails to initialize
the output error string--leading to tools (e.g., translate_et) returning
a null string; make afs_com_err fall back to returning the en/US canonical
error text when we don't have any i18n support...

Reviewed-on: http://gerrit.openafs.org/6638
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit ef63547e955edc60e2d074ef825b091e1c43882e)

Change-Id: Id138e48826aa855bd87e47f201ed6840399aa640
Reviewed-on: http://gerrit.openafs.org/6752
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>