Fix use of _LARGEFILE64_SOURCE

src/SDL_internal.h

@@ -28,7 +28,14 @@
 
 /* Need this so Linux systems define fseek64o, ftell64o and off64_t */
 #ifndef _LARGEFILE64_SOURCE
+#ifndef __QNX__
 #define _LARGEFILE64_SOURCE
+#else
+/* QNX expects either _LARGEFILE64_SOURCE to be defined as a value or not at
+   all.
+   As the comment above says _LARGEFILE64_SOURCE is for Linux, should it be
+   defined only if __LINUX__ is defined? */
+#endif
 #endif
 
 /* This is for a variable-length array at the end of a struct: