Refactor DiagnosticRenderer and SDiagsRenderer to have some functionality
pulled into DiagnosticNoteRenderer, and common DiagnosticRenderer that
assumes that all custom diagnostic messages are notes.  Also extend
DiagnosticRenderer to work with StoredDiagnostics in preparation for
subsequent changes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@150455 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed