coroapi.h: Make totem_mcast's *iovec param const.

• include/corosync/engine/coroapi.h (struct corosync_api_v1):

[totem_mcast]: Make *iovec param const.

git-svn-id: http://svn.fedorahosted.org/svn/corosync/trunk@2049 fd59a12c-fef9-0310-b244-a6a79926bd2f