DebugInfo: Rename DwarfCompileUnit.* to DwarfUnit.* to match their contents.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196140 91177308-0d34-0410-b5e6-96231b3b80d8
Update Release Notes for 3.4.1

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@208596 91177308-0d34-0410-b5e6-96231b3b80d8
Merge tag 'release-3.4.1' into powerpc-darwin8-rel-3.4