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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

Do you need to check if the lambda is templated?  For example, the following doesn't compile:

```
auto GetNonCapturingLambda() { return []<T>(){ return 42; }; }
auto f() { return GetNonCapturingLambda() == GetNonCapturingLambda(); }
```

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