Cleanup unnecessary includes for libskia.

The libskia target exports all of its public includes directories so
redefining them here is redundant. Also this cleans up and makes it
obvious where the framework is making using of private Skia headers.

Change-Id: Ie7ecc9ddd3df780bed6b9af54ba58ca58274e043
diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index 495ad19..2cc7a84 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -61,12 +61,7 @@
 	LOCAL_C_INCLUDES += \
 		$(JNI_H_INCLUDE) \
 		$(LOCAL_PATH)/../../include/utils \
-		external/skia/include/core \
-		external/skia/include/effects \
-		external/skia/include/images \
-		external/skia/src/core \
-		external/skia/src/ports \
-		external/skia/include/utils
+		external/skia/src/core
 
 	LOCAL_CFLAGS += -DUSE_OPENGL_RENDERER -DEGL_EGLEXT_PROTOTYPES -DGL_GLEXT_PROTOTYPES
 	LOCAL_CFLAGS += -Wno-unused-parameter