[libcxx-commits] [libcxx] [libc++] Remove ios_base::__xindex_ from the ABI (PR #198994)

[Volodymyr Turanskyy via libcxx-commits]

voltur01 wrote:

In ATfE we are building in single threaded mode (at least for now) so apparently `_LIBCPP_HAS_THREADS` was false, thus there was no use of atomic.

https://github.com/llvm/llvm-project/pull/198994