Enable stencil clipping within clearLayerRegions

bug:18538502

Cherry-pick of adc0d9da86 from AOSP

Previously stencil clipping within clearLayerRegions is disabled by commit
62d307c240. However, clearing whole layer
regions causes black-colored triangle regions when a TextView has
RotateAnimation because the draw within clearLayerRegions does not
affected by the current stencil clip.

Change-Id: Id32a0b16754b109905f833e063ebfa156bd953f2
Signed-off-by: Dohyun Lee <dohyun.lee@lge.com>

libs/hwui/OpenGLRenderer.cpp

@@ -1586,13 +1586,7 @@ void OpenGLRenderer::setupDraw(bool clearLayer) {
             setScissorFromClip();
         }
 
-        if (clearLayer) {
-            setStencilFromClip();
-        } else {
-            // While clearing layer, force disable stencil buffer, since
-            // it's invalid to stencil-clip *during* the layer clear
-            mCaches.stencil.disable();
-        }
+        setStencilFromClip();
     }
 
     mDescription.reset();