Race conditions sneaking in to concurrent testing

[WardF]

Several years ago, a lot of work went in to ensuring we could run our tests concurrently using either make check -j or ctest -j <# processors> for autotools and cmake-based builds, respectively.

There are mechanisms for ensuring tests which have dependencies on other tests run in the correct order. Looking in the Makefile.am and CMakeLists.txt files in the test directories should show these. I'm going to try to play whack-a-mole as these crop up, and we can also use ctest --schedule-random to run the tests in a random order (while still honoring the dependencies explicitly set in CMakeLists.txt), in order to help sniff out dependencies and potential race conditions.

@DennisHeimbigner @dopplershift