This prevents errors when encountering options which have been defined in newer
versions of clang-format, and are invalid in the YAML for the old version.
Bump minimum supported clang-format version to 12 (where `--Wno-error=unknown`
was added).
Use clang-format 12 on CI (13 is not available yet on the Ubuntu 20.04 images).
By generating stubs using https://github.com/hpvb/dynload-wrapper we
can dynamically load libpulse and libasound on systems where it is available.
Both are still a build-time requirement but no longer a run-time dependency.
For maintenance purposes the wrappers should not need to be re-generated
unless we want to bump pulse or asound to an incompatible version. It is
unlikely we will want to do this any time soon.
This closes#20978
It's too hard to get compatibility between GNU and BSD sed,
so let's just use perl oneliners.
And improve it to also remove trailing tabs, not just spaces.
