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.
llvm-svn: 150455
the policy of how diagnostics are lowered/rendered, while TextDiagnostic handles
the actual pretty-printing.
This is a first part of reworking SerializedDiagnosticPrinter to use the same
inclusion-stack/macro-expansion logic as TextDiagnostic.
llvm-svn: 146819