[DWARFLinker] Only extract unit DIEs when cloning clang modules (#69495)#7643

JDevlieghere merged 1 commit intostable/20230725swiftlang/llvm-project:stable/20230725from

cherrypick/rebranch/077d89f0ee84swiftlang/llvm-project:cherrypick/rebranch/077d89f0ee84Copy head branch name to clipboard