Don't automatically create a platform window on content orientation change

The platform window creation is policy is such that native resources are
created only when necessary. Since QWindow already tracks
contentOrientation, there is no reason to implicitly create a platform
window when a content orientation change is reported. This makes
content orientation follow the same convention used by windowState.
Merge pull request #15 from xknight/master

Don't automatically create a platform window on content orientation chan...