Fix missing ShadowMap headers in previous, da4e601d8f.

Tested on: gcc, clang

This was SVN commit r22606.

source/renderer/ShadowMap.cpp

@@ -24,6 +24,8 @@
 #include "ShadowMap.h"
 
 #include "graphics/LightEnv.h"
+#include "graphics/Camera.h"
+#include "graphics/Frustum.h"
 #include "graphics/ShaderManager.h"
 #include "gui/GUIMatrix.h"
 #include "lib/bits.h"

source/renderer/ShadowMap.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2012 Wildfire Games.
+/* Copyright (C) 2019 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -25,7 +25,10 @@
 #include "lib/ogl.h"
 
 class CBoundingBoxAligned;
+class CCamera;
+class CFrustum;
 class CMatrix3D;
+class CVector3D;
 
 struct ShadowMapInternals;