[libc++/abi] Allow running back-deployment testing against libc++abi

Before this patch, we could only link against the back-deployment libc++abi
dylib. This patch allows linking against the just-built libc++abi, but
running against the back-deployment one -- just like we do for libc++.

Also, add XFAIL markup to flag expected errors.

Differential Revision: https://reviews.llvm.org/D91069

GitOrigin-RevId: 60ba1fefab927af64bc8a03958661bb8c1412684
2 files changed
tree: 43dbabd0d12c750d85d0e75d42cc1652b75178a5
  1. .clang-format
  2. CMakeLists.txt
  4. cmake/
  5. docs/
  6. include/
  7. src/
  8. test/