const_cast in ExtFieldFinfo.h::strSet()

Created by: subhacom

ExtFieldFinfo is a new finfo to add new fields, dynamically, by addfield command. The strSet function, in ExtFieldFinfo, is const function, whose function is to set the value of a private variable. We also need to see that this added field is able to connect to other standard fields.

Currently, this has been handled by doing a const_cast.

Reported by: raameshd