[RF] Replace typeid with dynamic_cast in RooStatsUtils
[RF] Replace typeid with dynamic_cast in RooStatsUtils

This addresses Jira issue ROOT-4988.

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root