Enhance ceil tests.
Enhance ceil tests.

The tests are now explicitely testing, that no inexact
exception is raised.

Signed-off-by: Stefan Liebler <8bf38aec6ae5a260784bfd12203b32cefe7ce79a@linux.ibm.com>

gftg85/libdfp,gftg85/libdfp,gftg85/libdfp,gftg85/libdfp