handling of `easycrypt-prog-name` in `easycrypt-mode`

[chdoc]

For testing purposes, I was trying to get easycrypt-mode to use a different easycrypt binary than the one that's in the PATH as "easycrypt" (which is the sensible default value of easycrypt-prog-name).

However, it appears that any buffer-local settings of easycrypt-prog-name are completely ignored by easycrypt-mode. Hence, the following, which used to work for Coq, does not work for EC:

(* Local Variables: *)
(* easycrypt-prog-name: "~/git/easycrypt/ec.native" *)
(* End: *)

Moreover, even setting the variable globally (e.g., by executing (setq easycrypt-prog-name "~/git/easycrypt/ec.native") in *scratch* has no immediate effect. One can kill and restart easycrypt as often as one wants, one still gets the easycrypt binary. Only after setting easycrypt-prog-name globally and then executing M-x easycrypt-mode is the new setting taken into account.