Addition on C version of CFD-mini for comparison purposes (still serial)

For now I am adding a single c version of the CFD-mini benchmark. Next up will be naive parallel for both chapel and c.
Huh...maybe I made a mistake.  I simply did a "start_test" in that directory and thought I saw failures, but maybe something was out-of-date on my side.  Let me try again to double-check (hopefully I won't get distracted).

Ok, yeah, today I'm not seeing the failure I thought I was before.  Let's proceed with this and if it shows up again in the nightly regressions, we can scratch our heads some more.  Sorry for the confusion.