FYI - git-hooks updates to be deployed

[Joel Brobecker <brobecker@adacore.com>]

Hello,

Just a quick heads up to let everyone know that I'm about to update
the git-hooks on sourceware. I think the more interesting change is:

   - disable all checks (revision log, style) for commits created
     with "git revert". This uses a bit of a heuristic to identify
     those, but the idea is to avoid having additional roadblocks
     when trying to quickly revert a change which is known to be
     sufficiently problematic to need the revert.

     https://sourceware.org/gdb/wiki/GitHooksUsersGuide#A.22Revert.22_commits

Other changes, probably mostly irrelevant for the most part:

   - Add support for hooks.no-style-checks config option
     (I believe we don't do automated style-checking, at least not
     in binutils-gdb.git, so probably not relevant)

   - [AdaCore-specific] For repositories where a ticket number
     is required (hooks.tn-required set to True), the word "minor"
     in the revision log no longer waves that requirement. Instead,
     users are expected to use "no-tn-check", which is less likely
     to be used accidentally, and is also more explicit.

   - [Gerrit] Create an error when creating a branch where there is
     a .gitreview file pointing to a branch with a different name.
     This is mostly to remind users that when they create a new branch
     and push it, they should remember to update the defaultbranch in
     their .gitreview as well. Otherwise, things can become extremely
     confusing to users very quickly.

   - Some minor cleanups with no associated behavior change.

-- 
Joel