SurfaceFlinger: Skip composition when rotation is not completed

When rotating, each layer's buffer is already changed to
new orientation before SurfaceFlinger gets the signal from
Window Manager. If the orientations of all the buffers are
changed to new orientation, then that's fine. But, sometimes,
only one buffer is changed and others remain the same.
In this case, skip composition.

Change-Id: I850fe8ee6d806e21833e6811f95878fcfb6f7c40
CRs-fixed: 338034