[libcxx-commits] [libcxx] [libc++][NFC] Refactor _LIBCPP_AVAILABILITY_HAS_* macros to always be defined (PR #71002)

[via libcxx-commits]

wang-bin wrote:

another issue is `__libcpp_verbose_abort`, in libc++17 we can add `-D_LIBCPP_AVAILABILITY_HAS_NO_VERBOSE_ABORT=1` to be compatible with libc++<=16 runtime, but in libc++18 `_LIBCPP_AVAILABILITY_HAS_VERBOSE_ABORT` is always 1, the solution becomes ugly `-D_LIBCPP_VERBOSE_ABORT\(...\)=__builtin_abort\(\)`.

https://github.com/llvm/llvm-project/pull/71002