[PATCH] D29997: [libunwind][CMake] Use libc++ headers when available

[Petr Hosek via Phabricator via llvm-commits]

phosek added a comment.

This is a resubmit of https://reviews.llvm.org/D29800, turned out I need to use `LIBUNWIND_CXX_FLAGS` rather than `CMAKE_CXX_FLAGS` to avoid the `unused argument '-nostdinc++' ` error during linking.


Repository:
  rL LLVM

https://reviews.llvm.org/D29997