xfs: test correct propagation of rt extent size hints on rtinherit dirs

xfs: test correct propagation of rt extent size hints on rtinherit dirs

This is a regression test for the following fixes:

 xfs: standardize extent size hint validation
 xfs: validate extsz hints against rt extent size when rtinherit is set
 mkfs: validate rt extent size hint when rtinherit is set

These patches fix inadequate rtextsize alignment validation of extent
size hints on directories with the rtinherit and extszinherit flags set.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>