more splitting of Surface/SurfaceControl. Surface.java is now implemented in terms of Surface and SurfaceControl.

The WindowManager side of Surface.java holds a SurfaceControl, while the client-side holds a Surface. When the client is in the system process, Surface.java holds both (which is a problem we'll try to fix later).
diff --git a/include/ui/SurfaceComposerClient.h b/include/ui/SurfaceComposerClient.h
index a175a18..2a35256 100644
--- a/include/ui/SurfaceComposerClient.h
+++ b/include/ui/SurfaceComposerClient.h
@@ -62,7 +62,7 @@
     // surface creation / destruction
 
     //! Create a surface
-    sp<Surface>   createSurface(
+    sp<SurfaceControl> createSurface(
             int pid,            //!< pid of the process the surfacec is for
             DisplayID display,  //!< Display to create this surface on
             uint32_t w,         //!< width in pixel