Added macro so that targetconditionals.h isn't included when compiling from versions of Mac OS X earlier than 10.3 (the header file doesn't exist there). Instead, it is just assumed that you want to compile for Mac OS X rather than iPhone ... a fine assumption since you need 10.5 to compile for iPhone.
--- a/include/SDL_platform.h Fri Aug 15 18:31:30 2008 +0000
+++ b/include/SDL_platform.h Fri Aug 15 18:51:28 2008 +0000
@@ -59,15 +59,26 @@
#endif
#if defined(__APPLE__)
-#include "targetconditionals.h" /* Mac OS X 10.3 and later */
+/* lets us know what version of Mac OS X we're compiling on */
+#include "AvailabilityMacros.h"
+#ifdef MAC_OS_X_VERSION_10_3
+#include "targetconditionals.h" /* this header is in 10.3 or later */
#if TARGET_OS_IPHONE
+/* if compiling for iPhone */
#undef __IPHONEOS__
#define __IPHONEOS__ 1
#undef __MACOSX__
#else
+/* if not compiling for iPhone */
#undef __MACOSX__
#define __MACOSX__ 1
#endif /* TARGET_OS_IPHONE */
+#else
+/* if earlier verion of Mac OS X than version 10.3 */
+#undef __MACOSX__
+#define __MACOSX__ 1
+#endif
+
#endif /* defined(__APPLE__) */
#if defined(__NetBSD__)