Add dithering to gradients

Change-Id: Ic1208855bde3a254eca2fd7cef43e0f1318ce419
diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index a54c188..1947c32 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -11,6 +11,7 @@
 		Caches.cpp \
 		DisplayListLogBuffer.cpp \
 		DisplayListRenderer.cpp \
+		Dither.cpp \
 		FboCache.cpp \
 		GradientCache.cpp \
 		LayerCache.cpp \