testIntFire is not protected by DO_UNIT_TEST macro

Created by: subhacom

In file benchmark/benchmark.cpp functions are not always enabled. While the declaration of function (e.g. testIntFireNetwork) used in this file are enabled/disabled by DO_UNIT_TEST macro.

This is breaking the MOOSE build on launchpad where DO_UNIT_TEST is not defined.

Reported by: dilawar