- use per-module includes instead of "opencv.hpp"
- unused function warnings
- undefined macro warning

Found via `codespell -q 3 --skip="./3rdparty" -I ../opencv-whitelist.txt`

* Solve issue 7676

* I7676 bis

All of these: (performance) Prefer prefix ++/-- operators for non-primitive types.
[modules/calib3d/src/fundam.cpp:1049] -> [modules/calib3d/src/fundam.cpp:1049]: (style) Same expression on both sides of '&&'.