hi @smuzaffar (mostly)
having "cleaned up" (hopefully) a lot of CMSSW build files - I wonder if we can avoid altogether having developers maintain the lists of CMSSW packages in them? Eg, its easy to write a script (I did one) to find the set of packages with header dependencies and separately, those with dependencies in src (and plugins, etc).
BuildFiles could express external dependencies and other needed flags (well, many of those can be automated too but more complicated).
As an added bonus, this could allow us to separate include and lib dependencies if we wanted.