Update mod_exec to use the Jot API for resolving variables

[Castaglia]

The scope of this ticket is to update the mod_exec module's variable substitution code here to instead use the Jot API, so that it automatically benefits from new variable additions there.

[offsides]

I'm not really familiar with the jot API, but in principle this sounds like an excellent idea to centralize things and avoid code duplication.

[Castaglia]

I'm not really familiar with the jot API, but in principle this sounds like an excellent idea to centralize things and avoid code duplication.

The Jot API is ProFTPD's internal API that is used to resolve all of the LogFormat variables when writing e.g. ExtendedLog entries. It is also used, to support those LogFormat variables in things like SQLNamedQuery, and in logging modules like mod_redis and its ilk. So updating mod_exec to use this API as well (which it should be) is a Good Thing. I consider the fact that mod_exec does not use this API to be tech debt to be retired; it's one less place that implements its own handling of these variables.

[Castaglia]

Addressed in master now.