xfs: test extent size hint size overflows

xfs: test extent size hint size overflows

In certain cases, the extent size hints can cause maximum extent
size overflows resulting in extent tree corruptions. This test
exercises the original reproducer, and another corner case
demonstrated to expose problems on 1k block size filesystems.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
--
Version 2:
- TESTDIR->TEST_DIR
- append output to $seqres.full