LU-15748 osc: fallocate interop for 2.14 clients

LU-15748 osc: fallocate interop for 2.14 clients

fallocate() start and end are passed in o_size and o_blocks
on the wire.  Clients 2.15.0 and newer should always set
the OBD_MD_FLSIZE and OBD_MD_FLBLOCKS valid flags, but some
older client versions did not.  We permit older clients to
not set these flags, checking their version by proxy using
the missing OBD_CONNECT_TRUNCLOCK to imply 2.14.0 or older.

Test-Parameters: serverversion=2.14.0 testlist=sanity env=SANITY_EXCEPT="64h 103e"
Fixes: 2f496148c31d ("LU-15551 Return EOPNOTSUPP instead of EPROTO")
Fixes: 163870abfb7c ("LU-14382 mdt: implement fallocate in MDC/MDT")
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I1ea47854f40d54297bceb03ad32b24737efa4ae7
Reviewed-on: https://review.whamcloud.com/47098
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>