SourcePos leaks into the inherit shorthand

[Profpatsch]

inherit :: [NKeyName e] -> SourcePos -> Binding e
where before it was just inherit :: [NKeyName e] -> Binding e.
Same with inheritFrom.

As the shorthands module is for generating nix expression, not defaulting to nullPos doesn’t really make sense (since the user is not a parser and has no access to a filename or source position).

[jwiegley]

Agreed, @Profpatsch.