[clang] [clang] Accept lambdas in C++03 as an extensions (PR #73376)

[Chris B via cfe-commits]

https://github.com/llvm-beanz approved this pull request.

Sounds like this is all good from the C++ side. I'm fine with this bleeding into HLSL while we figure out what we need to do.

It would be super nice if we can just leave this enabled for HLSL as an extension. A lot of our users want it, but we may need to do some work to make that work within some of the other language constraints.

https://github.com/llvm/llvm-project/pull/73376