Various OpenGL optimizations

Change-Id: Ib0742c96f10f5f50e7e5148b742c31b6c232d127
diff --git a/libs/hwui/LayerRenderer.cpp b/libs/hwui/LayerRenderer.cpp
index 3f940bb..c30923f 100644
--- a/libs/hwui/LayerRenderer.cpp
+++ b/libs/hwui/LayerRenderer.cpp
@@ -458,6 +458,8 @@
         }
 
 error:
+        glEnable(GL_SCISSOR_TEST);
+
 #if DEBUG_OPENGL
         if (error != GL_NO_ERROR) {
             LOGD("GL error while copying layer into bitmap = 0x%x", error);