get rid of our LayerVector implementation

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

Change-Id: I910459cf3b3c8993b55ad0786a8c348369262de5
diff --git a/services/surfaceflinger/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index d5aa53f..75a9db5 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -39,8 +39,11 @@
 
 // ---------------------------------------------------------------------------
 
+int32_t LayerBase::sSequence = 1;
+
 LayerBase::LayerBase(SurfaceFlinger* flinger, DisplayID display)
     : dpy(display), contentDirty(false),
+      sequence(uint32_t(android_atomic_inc(&sSequence))),
       mFlinger(flinger),
       mNeedsFiltering(false),
       mOrientation(0),