rework processing of unavailable and deprecated attributes to avoid 
unneeded allocation of an empty StringLiteral when these don't have
a message.

llvm-svn: 126364
1 file changed
tree: 4ac50ed6795773860b6cbd0c939a0a39d02f5d64
  1. clang/
  2. compiler-rt/
  3. debuginfo-tests/
  4. libcxx/
  5. lldb/
  6. llvm/