[clang] [Clang] Allow parsing arbitrary order of attributes for declarations (PR #133107)

[Erich Keane via cfe-commits]

erichkeane wrote:

For #2 above, we'd not be able to figure out `[[foo, bar]]` from `[[foo]][[bar]]`, but maybe thats OK?  It gets WEIRD with using-namespaces though.

But otherwise I think this is reasonable.  

https://github.com/llvm/llvm-project/pull/133107