add .gitreview

A .gitreview file is required to use git review.
More information about git review
https://www.mediawiki.org/wiki/Gerrit/git-review

Change-Id: I03cbdf3a95bcf36a7388b5fa2652fd774b8f0f5b
Reviewed-on: https://gerrit.osmocom.org/68
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
1 file changed