I overrode clang-tidy where it uglified or obfuscated and did some
clean-up provoked or made possible by its changes. Konrad pointed out,
in review, a constructor that could be = default; it could, in fact,
vanish entirely as a result.
Pick-to: 6.6 6.5
Task-number: QTBUG-111228
Change-Id: I9b7744a3abaa29e6f9e0689d0f6985bfd88cd0fd
Reviewed-by: Konrad Kujawa <konrad.kujawa@qt.io>