LU-6544 mkfs: Improve MDT inode size calculation

LU-6544 mkfs: Improve MDT inode size calculation

This patch reduces mkfs.lustre "--stripe-count-hint" limits when
calculating MDT inode size, so that there is a proper amount of
space reserved for different kinds of EAs and ACL in the inode.

This would allow files with N stripes to fit the lov, lma, link
EAs into the inode rather than storing it in an external xattr
block, which reduces performance and significantly increases the
space used per file on the MDT.

Also, this patch adds conf-sanity.sh test_87 to verfiy this
calculation with different stripe count.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: Idfdd9a064f0ac07c383a3af79c61c1ff973fb3f7
Reviewed-on: http://review.whamcloud.com/15643
Tested-by: Jenkins
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>