How to use gflags with Ubuntu 14.04

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I'm so glad you asked Dave, turns out, according to the gflags developer:

This is more likely a problem of the Debian/Ubuntu package. Even though it suggests to contain gflags version 2.1, it's more likely version 2.0 given the list of files which was still using the auto tools for the build and installation. Or, the package maintainer decided to use the new source files with the old packaging tools. This, however, seems unreasonable given that there are no particular code changes besides the transition to CMake between these versions.

So we've added a FindGflags rule to cmake_modules in ROS Jade.