When sleeping waiting for either local or remote advisory lock,

When sleeping waiting for either local or remote advisory lock,
interrupt sleeps with the ERESTART on the suspension attempts.
Otherwise, single-threading requests are deferred until the locks are
granted for NFS files, which causes hangs.

When retrying local registration of the remotely-granted adv lock,
allow full suspension and check for suspension, for usual reasons.

Reported by:	markj, pho
Reviewed by:	jilles
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Approved by:	re (gjb)