* examples/calc++/test, examples/mfcalc/test (me): Be more
meaningfull: include the example name.
(prog): Factor.
(run): Avoid printf, use echo.
Add missing parens.
(cleanup): New.
Call it on trap.
Remove the previous "rm" that did the cleanup.
Move into a private directory to avoid concurrency issues.
Reported by Jim Meyering.