get rid of our LayerVector implementation

we now use SortedVector<> with a special compare implementation.

Change-Id: I910459cf3b3c8993b55ad0786a8c348369262de5
diff --git a/services/surfaceflinger/LayerBase.h b/services/surfaceflinger/LayerBase.h
index 4288cf7..22bf857 100644
--- a/services/surfaceflinger/LayerBase.h
+++ b/services/surfaceflinger/LayerBase.h
@@ -53,6 +53,8 @@
 
 class LayerBase : public RefBase
 {
+    static int32_t sSequence;
+
 public:
             LayerBase(SurfaceFlinger* flinger, DisplayID display);
 
@@ -61,6 +63,7 @@
             Region      visibleRegionScreen;
             Region      transparentRegionScreen;
             Region      coveredRegionScreen;
+            int32_t     sequence;
             
             struct State {
                 uint32_t        w;
@@ -210,12 +213,6 @@
     inline  const State&    currentState() const    { return mCurrentState; }
     inline  State&          currentState()          { return mCurrentState; }
 
-    static int compareCurrentStateZ(
-            sp<LayerBase> const * layerA,
-            sp<LayerBase> const * layerB) {
-        return layerA[0]->currentState().z - layerB[0]->currentState().z;
-    }
-
     int32_t  getOrientation() const { return mOrientation; }
     int  tx() const             { return mLeft; }
     int  ty() const             { return mTop; }