[clang] [clang] __is_trivially_equality_comparable for types containing lambdas (PR #68506)

[Amirreza Ashouri via cfe-commits]

AMP999 wrote:

> I think there is an opportunity for a small refactor here, but feel free to land this and we can handle the refactor later as an NFC change if you prefer

Is this (344455e) what you had in mind? I only found a few places that could use the factored-out function, and in the "CodeGenFunction.cpp" case, I'm not even sure it applies. It looks like that codepath is intended to be hit when we codegen the `operator()` of a lambda with captures under `-fsanitize=null`, but I couldn't see any null-check in the generated code even when the lambda did have captures, so I'm not sure I understand it. That codepath is 
@zygoloid's from 2017 (376c28e). Should I keep that diff, or revert it?

https://github.com/llvm/llvm-project/pull/68506