rwops: Fixed 64-bit file i/o on QNX.

src/file/SDL_rwops.c

@@ -18,8 +18,14 @@
      misrepresented as being the original software.
   3. This notice may not be removed or altered from any source distribution.
 */
+
+/* We won't get fseeko64 on QNX if _LARGEFILE64_SOURCE is defined, but the
+   configure script knows the C runtime has it and enables it. */
+#ifndef __QNXNTO__
 /* Need this so Linux systems define fseek64o, ftell64o and off64_t */
 #define _LARGEFILE64_SOURCE
+#endif
+
 #include "../SDL_internal.h"
 
 #if defined(__WIN32__)