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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Oh... GlobalValue::canBeOmittedFromSymbolTable is a rabbit-hole I didn't know existed.  Apparently I don't know how unnamed_addr works.  (canBeOmittedFromSymbolTable is completely inconsistent with the way everything else in the compiler reasons about unnamed_addr.)

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