[clang] [Clang] Skip past code generation for unevaluated lambdas (PR #124572)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

I would expect that we should instead be marking this function not `isUsed` (or `isReferenced`? ) to determine whether this should be emitted, and I would expect that to get caught in our existing infrastructure for that.

https://github.com/llvm/llvm-project/pull/124572