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

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

src/audio/bsd/SDL_bsdaudio.c

@@ -20,6 +20,8 @@
 */
 #include "SDL_config.h"
 
+#if SDL_AUDIO_DRIVER_BSD
+
 /*
  * Driver for native OpenBSD/NetBSD audio(4).
  * vedge@vedge.com.ar.
@@ -364,4 +366,6 @@ AudioBootStrap BSD_AUDIO_bootstrap = {
     "bsd", "BSD audio", BSDAUDIO_Init, 0
 };
 
+#endif /* SDL_AUDIO_DRIVER_BSD */
+
 /* vi: set ts=4 sw=4 expandtab: */