[clang] [CIR] Upstream initial TBAA implementation (PR #169226)

[Bruno Cardoso Lopes via cfe-commits]

bcardosolopes wrote:

> could you clarify what the CIR merge policy is, especially regarding authorship/attribution? I’m a bit concerned whether names from previous work might get dropped in the process.

What @andykaylor says below

> To be honest, we haven't been attempting to attribute authorship of the incubator changes. The official LLVM policy on upstreaming changes says that original authors should be attributed, and I'd be happy to do that on request, but the scope of the work to upstream the ClangIR incubator changes and the complexity of the history just makes it impractical to do that in general.

@PikachuHyA I yielded mine for the sake of progress, but I understand others might want different things. IANAL so I can't help much here.

https://github.com/llvm/llvm-project/pull/169226