[libcxx-commits] [libcxx] Revert "[libc++] Allow the use of extensions in the implementation (#79532)" (PR #85792)

[Sam McCall via libcxx-commits]

sam-mccall wrote:

Fixed a failure that showed up presubmit: "pair" is using explicit(bool) and needs a suppression similar to the one in tuple. So this is no longer a pure revert. (not sure why I didn't see this locally).

https://github.com/llvm/llvm-project/pull/85792