[llvm] [MC][Dwarf] Support DWARF Version 6 in CIE (PR #226997)

[David Spickett via llvm-commits]

https://github.com/DavidSpickett approved this pull request.

LGTM

The alternative was to change the test to use a triple that didn't hit this code, but it's always a shame to make a test less generic so I prefer this.

Include in the PR description the date of the snapshot you got this from. It'll probably be long gone before we care to look again, but might as well.

https://github.com/llvm/llvm-project/pull/226997