LLVM r236120 renamed debug info IR constructs to use a `DI` prefix, now
that the `DIDescriptor` hierarchy has been gone for about a week. This
commit was generated using the rename-md-di-nodes.sh upgrade script
attached to PR23080, followed by running clang-format-diff.py on the
`lib/` portion of the patch.
llvm-svn: 236121
Use new `DIBuilder` API from LLVM r224482 to mutate `DICompositeType`s,
rather than changing them directly. This allows `DIBuilder` to track
otherwise orphaned cycles when `CollectContainingType()` creates a
self-reference.
Fixes PR21941.
llvm-svn: 224483