DebugInfo/DWARF: Refactor type dumping to dump types, rather than DIEs that reference types
DebugInfo/DWARF: Refactor type dumping to dump types, rather than DIEs that reference types

This lays the foundation for dumping types not referenced by DW_AT_type
attributes (in the near-term, that'll be DW_AT_containing_type for a
DW_TAG_ptr_to_member_type - in the future, potentially dumping the
pretty printed name next to the DW_TAG for the type, rather than only
when the type is referenced from elsewhere)

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@348961 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm