LU-11963 osd: Add nonrotational flag to statfs

LU-11963 osd: Add nonrotational flag to statfs

It is potentially useful for the MDS and userspace to
know whether or not an OST is using non-rotational media.

Add a flag to obd_statfs that reflects this.

Users can override this parameter in proc.

ZFS does not currently make this information available to
Lustre, so default to rotational and allow users to
override.

Lustre-Change: https://review.whamcloud.com/34235
Lustre-Commit: 68635c3d9b3113621b93fd989f1a3f8f064385b9

LU-12396 utils: lfs should not output 'nul' char

If lfs prints a nul char, it breaks parsing of the output.

Fixes: 68635c3d9b31 ("LU-11963 osd: Add nonrotational flag to statfs")

Lustre-Change: https://review.whamcloud.com/35137
Lustre-Commit: fd3958b61c5f1c7ed520f07553b999af5522d8e0

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Iac2b54c5d8cc1eb79cdace764e93578c7b058661
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Signed-off-by: Minh Diep <mdiep@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35226
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>