Reviewer Alex - Use order dependencies for PHONY targets

As previously discussed, if you don't use order dependencies when using PHONY targets, make allows the builds to occur in parallel rather than serializing.  This means that building with `-j 2` or higher reports various coverage/valgrind errors since the results analysis occurs before the tests are run.

Solution is to use ordering rules (see https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.html for details) which cause the rules to be ordered.

If you're happy I'll port to Ralf/Homestead/Chronos/etc.
What about the `stage-build` and `test` targets?