LU-10391 socklnd: add hello message version 4

LU-10391 socklnd: add hello message version 4

KSOCK_PROTO_V4 uses a 'hello' message that contains
lnet_hdr_nid16 with 16 byte addresses

Test-Parameters: trivial
Test-Parameters: serverversion=2.12 serverdistro=el7.9 testlist=runtests
Test-Parameters: clientversion=2.12 testlist=runtests
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I52a36739d3a84dc059537059a586ce3dab2b20f0
Reviewed-on: https://review.whamcloud.com/43611
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Serguei Smirnov <ssmirnov@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>