[ticket/12161] Do not use subdirectories in build/save directory.

This is pretty much pointless because a new build will wipe the save directory
and there are only a few files in there anyway.

PHPBB3-12161
Merge pull request #1999 from bantu/ticket/11509

[ticket/11509] Further improvements/fixes for the Travis CI commit message checker
Merge pull request #2001 from bantu/ticket/12161

[ticket/12161] Do not use subdirectories in build/save directory.
[ticket/12162] Set language to C before running diff to ensure its english

PHPBB3-12162
Merge remote-tracking branch 'github-nickvergessen/ticket/12162' into develop-olympus

* github-nickvergessen/ticket/12162:
  [ticket/12162] Set language to C before running diff to ensure its english
[ticket/11509] Some load balancing: Run commit message checker in postgres env.

PHPBB3-11509
[ticket/11509] Three dots means sym. difference, but we only want new commits.

PHPBB3-11509
[ticket/11509] Output which commit is being inspected.

PHPBB3-11509
[ticket/11509] Exit with the expected (non-zero) exit status on failure.

PHPBB3-11509