Enable ARM64 support on LLVM builds

[konistehrad]

As suggested by @tritao in #1708 this PR adds support for building LLVM for ARM64 hosts, and adds ARM64 decompilation libs to the linkage.

[konistehrad]

@dotnet-policy-service agree

[konistehrad]

Tests are failing as the pulled LLVM will need to be rebuilt with DLLVM_TARGETS_TO_BUILD="X86;AArch64"

[tritao]

Tests are failing as the pulled LLVM will need to be rebuilt with DLLVM_TARGETS_TO_BUILD="X86;AArch64"

Spawned some LLVM builds:

https://github.com/mono/CppSharp/actions/runs/7760243198
https://github.com/mono/CppSharp/actions/runs/7760239936

[konistehrad]

Will I need to do anything special to point to these artifacts?

[tritao]

Will I need to do anything special to point to these artifacts?

Nope, after it finishes building, I'll need to replace the current builds on the releases page with these new ones. After that, the builds for this PR should hopefully progress.

[konistehrad]

Great. Thanks again for your assistance on this!

[tritao]

Can you update the PR with the new ARM64 CI builds: https://github.com/mono/CppSharp/blob/main/.github/workflows/main.yml#L12

[konistehrad]

Done!

[tritao]

My bad, those are failing of course, I thought you already added the new ARM64 parser bindings, but this PR is specifically for the LLVM support. 🤦

So feel free to remove that last commit and we can this one merged.

[konistehrad]

OK looks like the rest of the errors are predicated on updated bindings. Working on it now. EDIT: let me see if I can gen the bindings quick. I've got Mac headers, I'll collect Linux momentarily.

[konistehrad]

Nah you were right, this patch is too big for this PR. Gonna make a dependent branch and open another.