backward compat code

Author: gares

HB/common/log.elpi

@@ -71,7 +71,12 @@ env.add-const-noimplicits-failondup Name Bo Ty Opaque C :- std.do! [
 pred env.add-section-variable-noimplicits i:id, i:term, o:constant.
 env.add-section-variable-noimplicits Name Ty C :- std.do! [
   if (Name = "_") (ID is "fresh_name_" ^ {std.any->string {new_int}}) (ID = Name),
+% elpi:if version coq-elpi < 2.4.0
+  @local! => coq.env.add-section-variable ID Ty C,
+% elpi:endif
+% elpi:if version coq-elpi >= 2.4.0
   @local! => coq.env.add-section-variable ID _ Ty C,
+% elpi:endif
   log.private.log-vernac (log.private.coq.vernac.variable ID Ty),
   @local! => arguments.set-implicit (const C) [[]],
 ].