25fc52e655
The `_LIBCPP_DISABLE_AVAILABILITY` macro was removed in afae1a5f32bb as an intended no-op. It turns out that some projects are making use of that macro to work around a Clang bug with availability annotations that still exists: https://github.com/llvm/llvm-project/issues/134151. Since that Clang bug still hasn't been fixed, I feel that we must sill honor that unfortunate macro until we've figured out how to get rid of it without breaking code.