Stop pinning clang in windows ucrt

[jbourassa]

Ruby 3.4 + Windows is failing CI on wasmtime-rb, see this error.

Ruby 3.4 detects and uses <stdckdint.h> if it's present (source). For some reason, on Windows with that clang version the compiler thinks <stdckdint.h> is available, but then errors when includeing it.

I tried using the built-in clang version and looks like it worked, see this CI run, hence this PR.

[gjtorikian]

This should also close #46.

[gjtorikian]

I realized this morning I have merge permissions for this repo, so I created a test build for Commonmarker using this action: gjtorikian/commonmarker#335

Since it passed (thank you!), I was ready to merge this in, before realizing I don't have access to one thing: context. 😆 I'm not sure why this was pinned in the first place, so I don't feel comfortable merging it in without @ianks' 👀 .

[jbourassa]

IIRC, it was pinned to workaround incompatibilities between the latest bindgen version supported by rb-sys' MRSV and recent clang. But we're now on a more recent bindgen version, so that reason no longer applies.

I'm going off what I remember and could be wrong, I too would feel better if Ian had a look before merging.

[ianks]

annoyingly, i think bindgen breaks without clang-15 still :/ https://github.com/jbourassa/oxidize-rb-actions/actions/runs/12583936454/job/35072741493#step:8:4505

[jbourassa]

Ah, that's unfortunate, I don't know what's causing it nor how to fix it.

I tried updating bindgen in hope that it'd fix the issue (oxidize-rb/rb-sys#482), but that won't work given the recent bindgen require rust 1.70 (and the current MSRV is 1.65).

Not sure where to go from here.