[CodeView] Fix some Clang-tidy modernize-use-default, modernize-use-override and Include What You Use warnings; other minor fixes (NFC).

Per Zachary Turner and Mehdi Amini suggestion to make only post-commit reviews.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287243 91177308-0d34-0410-b5e6-96231b3b80d8
12 files changed