gnat-4.8 update

[Andrey Gursky <andrey.gursky@e-mail.ua>]

Hi,

While gcc 4.8.2 has been updated to 4.8.3, gnat-4.8 has gone except
gnat-4.8-doc [1].

Regards,
Andrey

[1]. https://packages.debian.org/search?keywords=gnat-4.8