fillRule() contained a major blunder: instead of checking if the
d-pointer was allocated, and return a default value if it wasn't,
it checked whether the path contained any points. This means that
QPainterPath p;
p.setFillRule(x);
Q_ASSERT(p.fillRule() == x);
was failing.
As a drive-by to test this change, fix another mistake in clear():
clear is documented to clear the elements in a path, but instead
it also changed the fill rule.
This commit partially reverses 697910e5fb.
Change-Id: Ieb8145694b672439c3380d9ccb87d1206a2dd115
Pick-to: 5.12 5.15 6.0 6.1
Done-with: Milian Wolff
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>