Clean up D3D 9 includes. Include d3d9 headers in one place only.

Added commented out define for D3D_DEBUG_INFO.
Uncomment it out for to debug DirectX objects.

panda/src/dxgsg9/dxIndexBufferContext9.cxx

@@ -21,7 +21,6 @@
 #include "config_dxgsg9.h"
 #include "graphicsStateGuardian.h"
 #include "pStatTimer.h"
-#include <d3dx9.h>
 
 #define DEBUG_INDEX_BUFFER false
 

panda/src/dxgsg9/dxVertexBufferContext9.cxx

@@ -23,7 +23,6 @@
 #include "pStatTimer.h"
 #include "internalName.h"
 #include "config_dxgsg9.h"
-#include <d3dx9.h>
 
 #define DEBUG_VERTEX_BUFFER false
 

panda/src/dxgsg9/dxgsg9base.h

@@ -32,6 +32,7 @@
 #include <windows.h>
 
 #define D3D_OVERLOADS   //  get D3DVECTOR '+' operator, etc from d3dtypes.h
+//#define D3D_DEBUG_INFO
 #include <d3d9.h>
 #include <d3dx9.h>
 #include <dxerr9.h>