build-sys: tweak to prevent dirty tree with every make

build-sys: tweak to prevent dirty tree with every make

Please let's stop the nls translation insanity. With a
one time push we can eliminate the dirty tree syndrome
which surfaces with every local build. Later, before a
release, the translations can be updated in final form
then pushed just 1 more time to the gitlab repository.

I'm tired of having to always re-issue this request in
order to circumvent the problem and thus prevent a too
broad commit (not to mention some nasty side effects).

[ bash$ git update-index --assume-unchanged po/??.po ]

Reference(s):
http://www.freelists.org/post/procps/procpsng-translations

Signed-off-by: Jim Warner <james.warner@comcast.net>