Let caller give pthread_cond_t to QuestionQueue

Also add a QuestionQueue which does not require
pthread_cond_t.

Parameterize QuestionQueue tests on the type on
QuestionQueue.
Implement eventfd and kqueue for QuestionQueue

Callers can create a QuestionQueue which will notify a give
eventfd or kqueue when something is enqueued.
Allow 'make TestProcess', etc.

Pass through MAKECMDGOALS to CMake's Makefile.  This lets
you type e.g. 'make TestProcess' to build the TestProcess
target.
WIP ProcessManager implementation