qttypes::QPainter unsound

[ogoffart]

QPainter is declared as a cpp_class!, but QPainter can't be moved in memory because the QPainterPrivate holds a q_ptr pointer to the origial QPainter.

qmetaobject-rs/qttypes/src/lib.rs

Lines 1279 to 1284 in 808d312

	cpp_class!(
	/// Wrapper around [`QPainter`][class] class.
	///
	/// [class]: https://doc.qt.io/qt-5/qpainter.html
	pub unsafe struct QPainter as "QPainter "
	);

We would need to somehow put the QPainter on the heap. But that'd be an incompatible change for people using it via the cpp! macro.