[PAC][libunwind] Fix gcc build of libunwind and compiler-rt (#164535)

This adds guards on the ptrauth feature checks so that they are only
performed if __has_feature is actually available.

GitOrigin-RevId: c1678e52f956f75f62d3240cf89d69c90b6505a4
3 files changed
tree: 8993fa14e9ec0b2f24187417961e4e4eabece2cb
  1. cmake/
  2. docs/
  3. include/
  4. src/
  5. test/
  6. .clang-format
  7. CMakeLists.txt
  8. LICENSE.TXT