a few small Makefile tweaks

I've added a few small tweaks here to the Makefile that hopefully don't conflict with the original purpose of some of these changes, but make docker actually build correctly from the Makefile for me again.

Of course, feel free to cherry pick or just reject altogether.  I made three separate commits to hopefully split this up into tiny chunks that make sense in case only one or two of them are acceptable, to make the cherry pick easier.  :)

As always, comments, questions, and concerns are always appreciated! :+1: