eliminate an useless message

tools/png2fimg.c

@@ -43,7 +43,10 @@ if (foo) {
 if (verbosity)	fimg_describe(&fimg, argv[2]);
 
 foo = fimg_dump_to_file(&fimg, argv[2], 0);
-fprintf(stderr, "save as fimg -> %d\n", foo);
+if (foo) {
+	fprintf(stderr, "save as '%s' -> err %d\n", argv[2], foo);
+	exit(1);
+	}
 
 return 0;
 }