update libwebp and libxml2

[henderkes]

What does this PR do?

• Closes new libxslt version fails build #981
• automatically updates libxml2, libwebp and go-xcaddy for new versions
• fixes build of pdo_sqlsrv from git, rather than a release tarball
• fixes liburing build for non-gcc on old linux header systems (rhel 8 and older)

This was what is required to build php 8.5 extensions (with 4 overridden source urls) by static-php/packages: see https://github.com/static-php/packages/blob/c5f504b532e394bd54391fa47501d7d07c6b03ee/config/templates/craft.yml.twig#L51

[crazywhalecc]

Speaking of which, I haven't set up any new command-line override rules for 3.0 yet. Besides the currently limited custom-url, custom-git, and custom-local options, what good methods do you think could be used to design a command-line overriding way?

The current version 3.0 (dev) allows users to register additional registry entries to override basic configs to let someone wants to override or expand functions on top of them. I don't know if it makes sense to continue expanding --custom-*, for common use.

Making another --custom={source_name}:{json} is very straightforward, but I don't think I'd even use it myself.

[henderkes]

I would say we scrap the custom url thing entirely and instead give users an option to add a second source.json?

We should chat about what features we no longer want to support and what we want to rework.

[crazywhalecc]

I would say we scrap the custom url thing entirely and instead give users an option to add a second source.json?

We should chat about what features we no longer want to support and what we want to rework.

All the implementation I made has been committed to the v3-dev branch. The refactoring status is in #980 . If you have any other ideas, free to leave a message on Discord or submit a new RFC.