Fix tests under GETTEXT_POISON on git-stash

Use i18n-specific test functions in test scripts for git-stash.
This issue was was introduced in v1.7.4.1-119-g355ec:

    355ec i18n: git-status basic messages

and been broken under GETTEXT_POISON=YesPlease since.

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t3903-stash.sh

@@ -610,7 +610,7 @@ test_expect_success 'stash apply shows status same as git status (relative to cu
 		git stash apply
 	) |
 	sed -e 1,2d >actual && # drop "Saved..." and "HEAD is now..."
-	test_cmp expect actual
+	test_i18ncmp expect actual
 '
 
 cat > expect << EOF