Remove forward-decleration of SkiaDisplayList

Enables DisplayList to be a wrapper around SkiaDisplayList
instead of a type-alias by having the full include of
SkiaDisplayList available

Test: builds
Change-Id: Ie906e6288530134840bee81af3a89871ed6a7d25
diff --git a/libs/hwui/DisplayList.h b/libs/hwui/DisplayList.h
index dd24763..dc63e5d 100644
--- a/libs/hwui/DisplayList.h
+++ b/libs/hwui/DisplayList.h
@@ -16,15 +16,14 @@
 
 #pragma once
 
+#include "pipeline/skia/SkiaDisplayList.h"
+
 namespace android {
 namespace uirenderer {
 
 namespace VectorDrawable {
 class Tree;
 };
-namespace skiapipeline {
-class SkiaDisplayList;
-}
 typedef uirenderer::VectorDrawable::Tree VectorDrawableRoot;
 
 /**