OA21-004 OB13-062 Fix of parsing counterexample model returned by cvc4.
OA21-004 OB13-062 Fix of parsing counterexample model returned by cvc4.

In a counterexample model returned by cvc4, values can be also of the form
"(mk_t__ref([0-9]*) (value))", while only the form "(mk_t__ref (value))"
was supported.

* src/driver/parse_smtv2_model_lexer.mll
MK_T__REF can be of the form "mk_t__ref([0-9]*)".

ssaavedra/why3,ssaavedra/why3,ssaavedra/why3