[libcxx] Add availability markup for bad_optional_access, bad_variant_access and bad_any_cast

Reviewers: dexonsmith, EricWF

Subscribers: christof, arphaman, libcxx-commits

Differential Revision: https://reviews.llvm.org/D53256

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347219 91177308-0d34-0410-b5e6-96231b3b80d8
50 files changed