t4030-diff-textconv: Make octal escape sequence more portable

There are printfs around that do not grok '\1', but need '\01'.
Discovered on AIX 4.3.x.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4030-diff-textconv.sh

@@ -29,7 +29,7 @@ test_expect_success 'setup binary file with history' '
 	printf "\\0\\n" >file &&
 	git add file &&
 	git commit -m one &&
-	printf "\\1\\n" >>file &&
+	printf "\\01\\n" >>file &&
 	git add file &&
 	git commit -m two
 '