Lots of fixes importing SDL source wholesale into a new iOS project

--HG--
rename : src/libm/math.h => src/libm/math_libm.h

src/video/windows/SDL_windowsmodes.c

@@ -20,6 +20,8 @@
 */
 #include "SDL_config.h"
 
+#if SDL_VIDEO_DRIVER_WINDOWS
+
 #include "SDL_windowsvideo.h"
 
 /* Windows CE compatibility */
@@ -316,4 +318,6 @@ WIN_QuitModes(_THIS)
     /* All fullscreen windows should have restored modes by now */
 }
 
+#endif /* SDL_VIDEO_DRIVER_WINDOWS */
+
 /* vi: set ts=4 sw=4 expandtab: */