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/uikit/SDL_uikitappdelegate.m

@@ -18,6 +18,9 @@
      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_UIKIT
 
 #import "../SDL_sysvideo.h"
 #import "SDL_assert.h"
@@ -159,4 +162,6 @@ static void SDL_IdleTimerDisabledChanged(const char *name, const char *oldValue,
 
 @end
 
+#endif /* SDL_VIDEO_DRIVER_UIKIT */
+
 /* vi: set ts=4 sw=4 expandtab: */