Remove bugged option MetaCoq Template Monad Debug.

It causes coq/vscoq#892 because `optwrite`
is not supposed to be able to add persistent objects (libobject) to
Coq's state but `set_option_value` does add one.

It's also bugged as
`set_option_value ~stage:Interp (fun _ v -> v) key i`
sets the option to its current value not a new value.
In other words `Set MetaCoq Template Monad Debug.` has no effect but
its existence causes bugs.

Since nobody complained about it not working it's not worth fixing it
instead of deleting it (also I'm not sure it can be fixed with the
currently available APIs).

template-coq/src/tm_util.ml

@@ -26,33 +26,6 @@ end = struct
     | None ->
       match declare_int_option_and_ref ~key ~value:0 () with { get } -> get
 
-  let set_template_monad_verbose =
-    let open Goptions in
-    match get_option_value key with
-    | Some get ->
-      let set = fun i ->
-        set_option_value ~stage:Interp (fun _ v -> v) key i
-      in set
-    | None -> assert false
-
-  let set_template_monad_debug d =
-    set_template_monad_verbose (if d then 1 else 0)
-  let get_template_monad_debug () =
-    if get_template_monad_verbose () > 0 then true else false
-
-  let _ =
-    let open Goptions in
-    let key = ["MetaCoq"; "Template"; "Monad"; "Debug"] in
-    match get_option_value key with
-    | Some get -> ()
-    | None ->
-      declare_bool_option
-        { optdepr  = None;
-          optstage = Interp;
-          optkey   = key;
-          optread  = get_template_monad_debug;
-          optwrite = set_template_monad_debug; }
-
   let ppdebug lvl pp =
     if get_template_monad_verbose () > lvl then Feedback.msg_debug (pp ())
 end