Enable transformations for Qt Quick in FT engine

In Qt Quick (or in Qt Widgets when setting QT_NO_FT_CACHE to 1 or
when using OpenGL engine), the alphaRGBMapForGlyph() will be used
to get glyphs, because we need to keep our own cache. Transforms
was not supported in this code path, instead it was turned off
in supportsTransformations().

This patch enables transformations in the alphaRGBMapForGlyph()
and alphaMapForGlyph() code paths as well, since this is needed
for proper rendering with QT_DEVICE_PIXEL_RATIO.

Change-Id: I7d6b79918f7c0bcc051a8343b16b315bfbba59cf
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>