FreeRDP/FreeRDP — pull request #671 by bmiklautz (2012-07-27 10:09:46+00:00)
Title: Add git version to --version when git is available

Now --version prints something like "This is FreeRDP version 1.0.1 (git
1.0.1-710-g90ec2)" (format: latest tag, commits since then, g+short unique id).
Having a git commit id helps to identify builds/versions and eases debugging.

The downside is that GetGitRevisionDescription retriggers a cmake
re-configuration after each git commit/checkout/... . But thats the only reliable way to get correct
version informations without having git hooks or similar.
If git or the revision is not available the is is either set to "" or to "n/a".

GetGitRevisionDescription is based on https://github.com/rpavlik/cmake-modules/blob/master/GetGitRevisionDescription.cmake.