[clang] [ItaniumCXXABI] Mark RTTI type name as global unnamed_addr (PR #111343)

[Richard Smith via cfe-commits]

zygoloid wrote:

@luxufan I think we may need changes on the LLVM side before we can make progress here -- either to clarify what `unnamed_addr` is intended to mean, or perhaps to split it into separate attributes for cloning and merging.

But before we go down that path, this PR doesn't describe the motivation for this change, so it'd be useful to get an idea of how much of a difference you expect this to make. Are you seeing a lot of duplicated symbols containing type manglings?

https://github.com/llvm/llvm-project/pull/111343