This includes a fix so that it doesn't transform declarations, and it
puts the functionality under control of a command-line option which is off
by default to avoid breaking existing setups.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@320196 91177308-0d34-0410-b5e6-96231b3b80d8
Dan Gohman