This *mostly* resembles our current coding style, at least to the extent
possible with clang-format.
There are a few oddities but they're not worth fighting over (for now)
and the most egregious violations have been addressed by shuffling
things around or just disabling clang-format in the previous commits.
Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1246>
