LU-12501 utils: fix 'lfs df' printing loop

LU-12501 utils: fix 'lfs df' printing loop

If the OS_STATE_NONROT flag is set for a device, the showdf() state
printing loop will spin endlessly because this bit is not printed,
so it is never cleared from the loop's state mask.

Declaring the obd_statfs_state_names[] array indexed by OS_STATE_*
flags also is problematic because the array will double in size as
new binary flags are added (already OS_STATE_NONROT results in an
array size of 0x200 = 512 entries).  Instead, declare a struct that
is indexed linearly and stores the OS_STATE_* flag in a field,
along with the name and whether the flag indicates a problem state.

The flag printing loop can iterate over the array of flags instead
of the os_state bits, which clarifies the for-loop iteration and is
equally efficient.

This also allows printing informational flags with "lfs df -v" so
that OS_STATE_NONROT and similar flags can be visible to users.

Fixes: 68635c3d9b3 ("LU-11963 osd: Add nonrotational flag to statfs")
Change-Id: Ib62e949ca56d691c4699d5f2d9439c42643ebbe5
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35456
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>