Add size option to sanlock direct dump
    
    Previously "sanlock direct dump" would stop when the first unused space
    was found in a lockspace or resource area. For example:
    
        $ sanlock direct init -r lockspace:A:leases:0
        $ sanlock direct init -r lockspace:B:leases:3145728
    
        $ sanlock direct dump leases
          offset    lockspace    resource  timestamp  own  gen lver
        00000000    lockspace           A 0000000000 0000 0000 0
    
    This patch adds optional size option. If specified, dump will search up
    to size bytes:
    
        $ sanlock direct dump leases:0:10485760
          offset    lockspace    resource  timestamp  own  gen lver
        00000000    lockspace           A 0000000000 0000 0000 0
        03145728    lockspace           B 0000000000 0000 0000 0
    
    Signed-off-by: Nir Soffer <nsoffer@redhat.com>