For some overly tight beziers where the start or end point and the
next control point are closer than the pen width, the stroker's
shifting algorithm will produce a start/end tangent pointing in the
opposite direction from what is expected, for one of the sides. This
would break the square and round capping logic. Fix by detecting the
situation in the capping function and reversing the tangent when
necessary.
Change-Id: I48f4f017403d7b289b0483dd2b3a7ff1bbd0cf2a
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
