Now remmina version show something like "1.2.0-rcgit.8 (git 194cc9d)"

Having a git commit id helps to identify builds and eases
debuggin.

The downside is that GetGitRevisionDescription retriggers a cmake
re-configuration after each git commit. But thats the only way to get correct
version informations without having git hooks or similar.

GetGitRevisionDescription is based on Ryan Pavlik cmake Modules and @bmiklautz
patch 32390d78 in FreeRDP