Update comment slightly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186548 91177308-0d34-0410-b5e6-96231b3b80d8
Get rid of the Dis/EnableDebugLocations() API.
I'm moving this functionality into clang instead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186549 91177308-0d34-0410-b5e6-96231b3b80d8