sanlock/wdmd: remove global connection
    
    As long as the sanlock daemon was running, it kept a
    constant connection to wdmd, even when no lockspaces
    existed.  This prevented sanlock and wdmd from being
    restarted independently, even when they were unused.
    Independent restarting is necessary for upgrades, so
    remove the global connection from sanlock to wdmd and
    leave only the per-lockspace connections.  The lockspace
    connections now need to hold a refcount on wdmd which
    prevents wdmd restarts.
    
    Also in wdmd, if a client connection is closed, the
    refcount must not be cleared on it, otherwise wdmd
    could possibly be cleanly shutdown from sigterm while
    an expired connection was awaiting a watchdog reset.
    
    Also log at the error level when we kill a pid for
    recovery, when that pid exits, and when all pids
    are clear for recovery.  This makes it much simpler
    to see exactly what led up to a watchdog reset
    after the fact.
    
    Signed-off-by: David Teigland <teigland@redhat.com>