CI patches that are not in series file QA

[Harald Sitter]

Another alohas

While working on our patch parser today I noticed that there is a
rather unfortunately large amount of patches that get removed from the
series file but not from git (not until someone notices that they are
unused anyway).
So, I just deployed an all new QA measure checking for that and
turning CI builds unstable where the contents of patches/ doesn't add
up with what is listed in patches/series.

Random note: since genuine upstream patches do get removed from CI
branches they would potentially still dangle in a landing branch (e.g.
kubuntu_vivid_archvie) if not removed correctly. This situation would
however ultimately auto-resolve when whatever currently used landing
branch gets a CI branch merged (i.e. the upstream branch would then
definitely be removed).

HS