Remove "range_iterator" from PathDiagnosticPiece and just use ArrayRef<SourceRange> for ranges.  This 
removes conceptual clutter, and can allow us to easy migrate to C++11 style for-range loops if we
ever move to using C++11 in Clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162029 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed