dlm: increase max number of links for corosync3/knet

This patch increases the maximum number of links that can be
used with corosync3/knet. The majority of the changes are in
user space dlm_tools/dlm_controld.

Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Signed-off-by: David Teigland <teigland@redhat.com>