Merge branch 'jk/update-git' into pu

* branch jk/update-git:
  WIP - currently pointing at a random point on Git's maint branch

Waiting for the next maint release of Git.
Merge branch 'jk/compat-timegm' into pu

* branch jk/compat-timegm:
  compat/timegm: new compat function for systems lacking timegm()
  Makefile: re-include cgit.conf in cgit.mk

Submitted to cgit@hjemli.net.
Merge branch 'jk/use-git-test-framework' into pu

* branch jk/use-git-test-framework:
  tests: use Git's test framework

Submitted to cgit@hjemli.net.

Could use Sharness instead of Git's test framework.

Can have several tidy-ups built on top if there is agreement that this
is the right way to go.
Merge branch 'jk/no-sed-i-in-tests' into pu

* branch jk/no-sed-i-in-tests:
  tests: sed -i is not portable

Currently dogfooding locally.