Method evaluatePointerExpression

\brief Determine if the expression rooted at the given INT_ADD operation is ready for conversion Converting an expression of INT_ADDs into PTRSUBs and PTRADDs requires that the base pointer be at the root of the expression tree. This method evaluates whether given root has the base pointer at the bottom. If not, a \e push transform needs to be performed before RulePtrArith can apply. This metho