Add LibreOffice build-deps.

These are the dependencies that i needed in a VM with a "Debian Jessie netinst" installation. I had in the system the "Standard system utilities", fdroidserver, all the packages listed in "buildserver/cookbooks/fdroidbuild-general/recipes/default.rb", and "build-essential". I assume that the BS has build-essential installed as its needed to build the "VirtualBox Guest Additions".