[clang] [Sema] Avoid repeated hash lookups (NFC) (PR #109375)

[Nikita Popov via cfe-commits]

https://github.com/nikic commented:

Hm, why does this wrapper exist at all? It looks like a trivial wrapper that doesn't add or change any DenseMap functionality.

https://github.com/llvm/llvm-project/pull/109375