Automatic builds of clang using OBS

Description of the project: Currently, builds with clang are only done from time to time. This is done through a massive rebuilds of the archive on AWS. Results are published on http://clang.debian.net/ (sources & data: https://github.com/opencollab/clang.debian.net). The idea is to automate this so that the clang link on the right https://packages.qa.debian.org/f/firefox.html) points to the OBS CI.

Two similar projects are proposed under the LLVM umbrella: http://llvm.org/OpenProjects.html#apt