[clang] Fix the double space and double attribute printing of the final keyword. (PR #88600)

[Kim Gräsman via cfe-commits]

kimgr wrote:

> I am wondering if that'd be interesting and if so, maybe we can share it between both projects via upstreaming to Clang...

That sounds fantastic, but mostly because I don't have anything to offer, and everything to benefit :)

I was just thinking about adding a `.ForwardDeclaration` policy to `DeclPrinter` this morning -- the current `PolishForDeclaration` output is _so_ close. But it seemed weird to add a mode for which IWYU (a non-LLVM project) was the only user.

I suspect your `ForwardDeclarePrinter` is more principled. I guess it might be hard to coordinate forward-decl style between users, but ultimately that's just printing policy (or chaining libFormat, or something).

Let's maybe continue this discussion somewhere else?

https://github.com/llvm/llvm-project/pull/88600