[NFC] Refactor DiagnosticRenderer to use FullSourceLoc

Move the DiagnosticRenderer and its dependents to using FullSourceLocs
instead of a SourceLocation and SourceManager pointer. The changeset is
rather large but entirely mechanical.

This is step one to allow DiagnosticRenderer to take either
llvm::SMLocs or clang::SourceLocations.

Patch by Sanne Wouda

Review: https://reviews.llvm.org/D31709

Change-Id: If351a112cdf6718e2d3ef6721b8da9c6376b32dd
llvm-svn: 305684