Remove LayerRenderer.

There is only one caller each for the static functions here so this
CL moves the logic to the caller.  Also by moving some of the code
into the pipeline it makes it easier for future changes to configure
how a pipeline handles a layer.

Change-Id: Ib735b5154325cbb658fd151f7a19dbf434ab44b7
diff --git a/libs/hwui/Layer.cpp b/libs/hwui/Layer.cpp
index b911b68..4e12bce 100644
--- a/libs/hwui/Layer.cpp
+++ b/libs/hwui/Layer.cpp
@@ -41,7 +41,7 @@
     // TODO: This is a violation of Android's typical ref counting, but it
     // preserves the old inc/dec ref locations. This should be changed...
     incStrong(nullptr);
-    renderTarget = GL_TEXTURE_2D;
+    renderTarget = GL_NONE;  // see DeferredLayerUpdater::updateLayer()
     texture.mWidth = layerWidth;
     texture.mHeight = layerHeight;
     renderState.registerLayer(this);