* ci: update Makefile
- Copied from c5c5149583/copythis.circleci/Makefile
* Makefile: make ci- targets phony and more explicit
* ci: add pre-flight checks
- Right now just validates ci config is up to date.
* ci: add --skip-update-check to circleci
* ci: remove cruft from Makefile
* ci: fix missing source dir error message
* ci: consolidate circleci path handling
