Explicitly disallow the caca driver. (It's caca)

src/conio/sdl_con.c

@@ -1383,7 +1383,7 @@ int SDL_main_env(int argc, char **argv, char **env)
 	}
 	if(sdl.VideoDriverName(drivername, sizeof(drivername))!=NULL) {
 		/* Unacceptable drivers */
-		if((!strcmp(drivername,"aalib")) || (!strcmp(drivername,"dummy"))) {
+		if((!strcmp(drivername, "caca")) || (!strcmp(drivername,"aalib")) || (!strcmp(drivername,"dummy"))) {
 			sdl.gotfuncs=FALSE;
 			sdl.Quit();
 		}