719bf2d9d9
Add a warning and tweak the release note to explain that the deprecation targets libc++, libc++abi and libuwnind as well. Also, as a fly-by, ensure that our CI runs the legacy testing configuration for libc++, libc++abi and libunwind. This doesn't matter too much since it's deprecated, but we might as well test it properly. Differential Revision: https://reviews.llvm.org/D126478