[clang] [lldb] [clang][AST] fix ast-print of extern <lang> with >=2 declarators, fixed (PR #93913)

[Artem Yurchenko via cfe-commits]

temyurchenko wrote:

This is a relanding of #93131. 

The first commit is the same, the second commit presents and fixes the issue from the linked discussion.

cc @erichkeane, @AaronBallman, @gulfemsavrun.
(I can't set the reviewers myself)

https://github.com/llvm/llvm-project/pull/93913