Some QColor::setX() functions do not invalidate instance

The QColor functions setRgb(), setHsv(), setHsl(), setCmyk() together with their float variants set...f() all check the incoming values but are inconsistent in clearing the QColor instance on invalid input.

I attached the current (2017-08-11) head revision of qcolor.cpp as well as a patched version of that file with all missing calls to invalidate() added.

This patch would change current behavior:
For example, setCmyk() currently preserves the original QColor on invalid input, after the patch it would invalidate().
So it probably targets Qt6.