[clang] [llvm] Enable ClangIR Build By Default (PR #221291)

[Nikita Popov via cfe-commits]

https://github.com/nikic requested changes to this pull request.

Can you please make sure this works with the dylib build?

Currently this fails to link for the full build, and if you build just clang the binary is completely broken.

https://github.com/llvm/llvm-project/pull/221291