Possibly rework `docker-php-source` to account for patches

We added a couple backports to `8.1` from PHP upstream changes to get it to compile on Alpine 3.21 in #1552. We should consider keeping them around so that they can be applied with `docker-php-source extract` in case the patches we backport also apply to extensions we don't compile in (or users that recompile the already built-in extensions).