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_windowsevents.c

@@ -18,9 +18,10 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
-
 #include "SDL_config.h"
 
+#if SDL_VIDEO_DRIVER_WINDOWS
+
 #include "SDL_windowsvideo.h"
 #include "SDL_windowsshape.h"
 #include "SDL_syswm.h"
@@ -694,4 +695,6 @@ SDL_UnregisterApp()
     }
 }
 
+#endif /* SDL_VIDEO_DRIVER_WINDOWS */
+
 /* vi: set ts=4 sw=4 expandtab: */