weekly build system fixes

Weekly build fixes, the 497516871587th edition: The cleanup towards a completely pattern-driven Makefile continues.  There's not much left where this came from, but I guess I have promised that before.  As one lifts off layers of repetition and streamlines the structure, more opportunities for refactoring present themselves.

Nonetheless I hope to soon switch all the -make rules to a pattern as well, maybe even in the pull request following this one.