The full stroker does not produce good results for aliased lines
thinner than 1 pixel. Avoid it by making sure that such thin lines
are painted by the cosmetic stroker, even when they have
non-uniform transformation.
Fixes: QTBUG-73866
Change-Id: I7b5f0fa555903246e0c3fd92cd435cc8c0b15a24
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>