Make unlinker open a gdt file if not raw specified

src/ObjWriting/Dumping/AssetDumpingContext.cpp

@@ -0,0 +1,6 @@
+#include "AssetDumpingContext.h"
+
+AssetDumpingContext::AssetDumpingContext()
+    : m_zone(nullptr)
+{
+}

src/ObjWriting/Dumping/AssetDumpingContext.h

@@ -2,6 +2,7 @@
 
 #include <string>
 
+#include "Obj/Gdt/GdtStream.h"
 #include "Zone/Zone.h"
 
 class AssetDumpingContext
@@ -9,4 +10,7 @@ class AssetDumpingContext
 public:
     Zone* m_zone;
     std::string m_base_path;
+    std::unique_ptr<GdtOutputStream> m_gdt;
+
+    AssetDumpingContext();
 };