Add a __has_attribute macro that works much like __has_feature and __has_builtin.

llvm-svn: 116906
10 files changed
tree: fccdd5042be19eff3d1c109477cdf047af8c70b8
  1. clang/
  2. compiler-rt/
  3. debuginfo-tests/
  4. libcxx/
  5. lldb/
  6. llvm/