Fix issue #2095422: Some fades from opaque to transparent don't work

ViewRoot was using Surface.clear(), which has different behavior
in different processes -- in the system process it would kill the
surface, causing all windows in that process to immediately disappear
instead of animating away.

This change makes Surface.release() public and uses that instead.  It
also renames Surface.clear() to Surface.destroy().

Also fixed some issues in the window manager that were causing the
wallpaper to not get immediately resized when the orientation changes
and its target window is removed and re-added.

Change-Id: I2a992e365cf5747511f0bf1193db32dc2525b218