[php-src] Issue #13877: [Chore] Officially support musl the same way glibc is supported

Issue: https://github.com/php/php-src/issues/13877 Author: dkarlovi ### Description From what I've understood talking to people closer to the project, musl is seen as an afterthought in PHP, it mostly works, but isn't seen as a priority. This creates issues like performance issues and weird bugs for musl users: https://github.com/dunglas/symfony-docker/issues/555 https://github.com/php/php-src/issues/11678 While musl is not as used as glibc, it does have a strong presence when using with containers (Alpine based images) and also new directions PHP can take, like with FrankenPHP standalone binaries using static-php (which uses musl) All this means musl usage is not insignificant and is quite likely to become larger with time, it would make sense to include running correctly on musl as a requisite for a release, include musl for performance regression tests, etc.