LU-11146 lustre: fix setstripe for specific osts upon dir

LU-11146 lustre: fix setstripe for specific osts upon dir

LOV_USER_MAGIC_SPECIFIC function is broken and it
was not available for setting directory.

1)llite doesn't handle LOV_USER_MAGIC_SPECIFIC case
properly for dir {set,get}_stripe, and ioctl
LL_IOC_LOV_SETSTRIPE did not alloc enough buf,
copy ost lists from userspace.

2)lod_get_default_lov_striping() did not handle
LOV_USER_MAGIC_SPECIFIC type that newly created
files/dir won't inherit parent setting well.

3)there is not any case to cover lfs setstripe
'-o' interface which make it hard to figure out
when this function was broken.

Change-Id: Icc2ee60a474e5e565db12b35a9a38fde65b05bbd
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/32814
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>