teeing output into result file

Note that functions with "| tee" to keep test output into result files
run in sub-processes. This means that global variable like TESTCASE,
SUCCESS, and FAILURE is not counted up correctly.
So if you write your own checker function, you should make sure that
your test output is teed out into $OFILE.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>