Automatic builds with clang using OBS

Debian package builds with clang are performed from time to time through massive rebuilds of the Debian archive on AWS. The results of these builds are published on clang.debian.net. This summer project aims to automate Debian archive clang rebuilds by substituting the current clang build service with the Open Build System (OBS). By the end of the summer, the clang links on the right corner of QA package pages will point to a new OBS clang CI, which will constantly provide up to date clang build results of the whole Debian archive.