[clang] [clang][Sema] fix crash on __type_pack_element with dependent packs (GH180307) (PR #180407)

[via cfe-commits]

Serosh-commits wrote:

@ojhunt @mizvekov i don't have commit access:) would be happy if someone would land the merge 


https://github.com/llvm/llvm-project/pull/180407