Instead of printing an URL with each warning, print one once at the
end. This gives less cluttered output, and we don't have information
about each and every option on that wiki page anyway (and given that we
now have so many options, I don't think it's good use of time to add it
there.)
Abort the "pmbootstrap kconfig check" on the first error, unless the
--keep-going argument was passed. This makes it easier to go through the
failed kernels one by one until they are all fixed.
