clm.c:
defect 642
fix segfault when null clusterNode parameter passed to saClusterNodeGet

BKrev: 42b31bd8J6eYpNHnpFWwHWc3waURXw


git-svn-id: http://svn.fedorahosted.org/svn/corosync/trunk@702 fd59a12c-fef9-0310-b244-a6a79926bd2f