[clang] [clang] Support `__is_trivially_copyable(int()&)==false` (PR #81298)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

I think the former diagnostic is more clear. It seems the issue is around here: https://github.com/llvm/llvm-project/blob/d7975c9d93fb4a69c0bd79d7d5b3f6be77a25c73/clang/lib/Parse/ParseDecl.cpp#L2828

We changed the `DeclSpecContext` so we hit the `else if` rather than the `if` because of `isTypeSpecifier()`.

https://github.com/llvm/llvm-project/pull/81298