examples: fix the test suites.

examples: fix the test suites.

	* 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.