Refactor glyph pretransform check

Refactor glyph pretransform check

Move paintEngineSupportsTransformations logic from QPainter to paint
engine subclasses. Simplify and consolidate checks for cached drawing
(pretransformed) and path drawing (untransformed) in raster paint
engine. Fix unnecessary transform when paint engines actually take
the path drawing track. Fix scaling and rotation transform in raster
engine for Mac.

Task-number: QTBUG-19086
Change-Id: I1c0c1800a5173d3db765b9fccfd0e7a3628e3815
Reviewed-on: http://codereview.qt.nokia.com/298
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@nokia.com>