Add srfi-253 to 6 coop

[Artyom Bologov via Chicken-users]

Hi y’all,

Can you add srfi-253 <https://gitlab.com/ThatGeoGuy/srfi-253> to Chicken
6 coop? I believe it works on version 6.

Thanks,
-- 
Artyom Bologov
https://aartaka.me