Clear orientation variable until rotation is done.

In the old code orientationChangeComplete was set to true on each pass
through perfomLayout. If any window was rotating the variable was set
to false on the way through the performLayout. Since we can now make
passes through performLayout before any animation step occurs we were
seeing mOrientationChangeComplete true prior to rotation completing.

This change sets mOrientationChangeComplete false at the start of a
rotation and sets it to true if we ever get through an animation step
without encountering any rotating windows.

Change-Id: I37690cf20868dfbaac94a81640bc4d9cb9fb8f00