​Isorropia: Remove Build Warnings

Created by: ZUUL42

Enhancement

@trilinos/​Isorropia

Issue #3178 is working toward turning Warnings as Errors on for all packages in order in ensure Trilinos maintains a high level of SQA practices across the project. Currently ​Isorropia has a warning that need to be handled before we can set Werror for ​Isorropia and eventually all packages.

A recent test build was performed with -Werror set. The CDash report can be found here. Once the ​Isorropia build doesn't emit any warnings that will be promoted to errors, we can set -Werror in the GCC 7.2.0 automated build.