Fix tst-strcoll-overflow returning before timeout (BZ #17506)

Fix tst-strcoll-overflow returning before timeout (BZ #17506)

Modifies the test examination in test-skeleton.c so that a test can be
successful if it is interrupted or it returns uninterrupted with the
expected status. For this both EXPECTED_SIGNAL and EXPECTED_STATUS
have to be set, as is done in tst-strcoll-overflow.c.