Use __atomic_exchange_n instead of Clang's __sync_swap

Also remove an extra extern "C" from a global variable redeclaration.
This allows building libcxxabi with GCC on my system.

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D5604

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@219012 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed
tree: a020ac68153c5d3652b05fbab5e8124c28f66641
  1. CMakeLists.txt
  2. CREDITS.TXT
  3. LICENSE.TXT
  4. cmake/
  5. include/
  6. lib/
  7. src/
  8. test/
  9. www/