surfaceflinger: pass RenderEngine into BufferLayerConsumer

Add RenderEngine::isCurrent to replace
BufferLayerConsumer::checkAndUpdateEglStateLocked.  Remove a
duplicated check in updateAndReleaseLocked.  Use
RenderEngine::checkErrors.

Test: SurfaceFlinger_test
Change-Id: I6b97534a41a855d101965b498cb1afa72404227e
diff --git a/services/surfaceflinger/RenderEngine/RenderEngine.h b/services/surfaceflinger/RenderEngine/RenderEngine.h
index 57662a4..f886919 100644
--- a/services/surfaceflinger/RenderEngine/RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/RenderEngine.h
@@ -86,6 +86,10 @@
 
     bool supportsImageCrop() const;
 
+    bool isCurrent() const;
+    bool setCurrentSurface(const RE::Surface& surface);
+    void resetCurrentSurface();
+
     // synchronization
 
     // flush submits RenderEngine command stream for execution and returns a
@@ -124,9 +128,6 @@
         int getStatus() const;
     };
 
-    bool setCurrentSurface(const RE::Surface& surface);
-    void resetCurrentSurface();
-
     // set-up
     virtual void checkErrors() const;
     virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop, size_t hwh,