Revert "Support: Partially revert r249782 to unbreak clang build"

This reverts commit r249783, fully reinstating r249782.  I've fixed the
bug in clang: it was a non-const iterator that dereferenced to const
(but had an implicit conversion to non-const).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249850 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed