Fix references to d3dx12

DDSTextureLoader/DDSTextureLoader12.cpp

@@ -24,7 +24,7 @@
 #include <algorithm>
 #include <memory>
 
-#include <d3dx12.h>
+#include "d3dx12.h"
 
 using namespace DirectX;
 

ScreenGrab/ScreenGrab12.cpp

@@ -35,7 +35,7 @@
 
 #include <wrl\client.h>
 
-#include <d3dx12.h>
+#include "d3dx12.h"
 
 using Microsoft::WRL::ComPtr;
 

WICTextureLoader/WICTextureLoader12.cpp

@@ -34,7 +34,7 @@
 
 #include <wrl\client.h>
 
-#include <d3dx12.h>
+#include "d3dx12.h"
 
 using namespace DirectX;
 using Microsoft::WRL::ComPtr;