#include <stdlib.h> and add the prototype for XPDEV_main()

src/xpdev/sdlfuncs.c

+#include <stdlib.h>	/* getenv()/exit()/atexit() */
 #include <stdio.h>	/* NULL */
 
 #include "gen_defs.h"
@@ -13,6 +14,8 @@ static int sdl_initialized=0;
 static int sdl_audio_initialized=0;
 static int sdl_video_initialized=0;
 
+int XPDEV_main(int argc, char **argv, char **enviro);
+
 #ifdef STATIC_SDL
 int load_sdl_funcs(struct sdlfuncs *sdlf)
 {