Localization for the day suffix

[iluha5]

It seems like suffixes with S flag are hardcoded.
S: ['th', 'st', 'nd', 'rd'][d % 10 > 3 ? 0 : (d % 100 - d % 10 != 10) * d % 10],

Is it possible to move them to DateFormatI18n object?
Is there another way to localize such suffixes?

Thanks.