If the cm_scache_t flags include CM_SCACHEFLAG_DELETED, do not
bother releasing an outstanding file lock to the file server.
The lock went away when the file was deleted. Any attempt to
release will fail with VNOVNODE which is translated locally into
CM_ERROR_BADFD.
If a RXAFS_ReleaseLock RPC fails with VNOVNODE, treat it as
success.