WINCE: Enable use of forbidden symbols, cleanup

I tried to untangle the header interdependencies a bit, but this
is still quite a mess.
This commit also fixes some warnings.

svn-id: r53978

backends/platform/wince/CEgui/SDL_ImageResource.cpp

@@ -23,6 +23,10 @@
  *
  */
 
+// Disable symbol overrides so that we can use system headers.
+#define FORBIDDEN_SYMBOL_ALLOW_ALL
+
+#include "SDL.h"
 #include "SDL_ImageResource.h"
 
 namespace CEGUI {