Fixed build warning on iOS

include/SDL_config_iphoneos.h

@@ -134,6 +134,7 @@
 #define HAVE_NANOSLEEP  1
 #define HAVE_SYSCONF    1
 #define HAVE_SYSCTLBYNAME 1
+#define HAVE_O_CLOEXEC 1
 
 /* enable iPhone version of Core Audio driver */
 #define SDL_AUDIO_DRIVER_COREAUDIO 1

src/SDL_internal.h

@@ -51,7 +51,7 @@
 
 #include "SDL_config.h"
 
-#ifndef HAVE_O_CLOEXEC
+#if !defined(O_CLOEXEC) && !defined(HAVE_O_CLOEXEC)
 #define O_CLOEXEC                       0
 #endif