I'm opening this bug to avoid repeating bug1164454 - SP3 is supposed to get
an update to the Mesa LLVM stack again, this time I will pick llvm11.  Again
SLE 15 SP3 will keep llvm7 as 'llvm' and from the llvm11 set of packages only
what is required for Mesa will end up on the media (no clang, etc.) but all
this "rest" should be diverted to PackageHub.

Since there's that new Jump thing on the plate for Leap 15.3 and Leap 15.3
traditionally wants clang to be new and not old I wonder how we can make
these conflicting requirements work this time.

My current plan is to simply throw what's in Factory into SP3 and put a big
fat note on it what (sub-)packages to ship and what not.