- add an AST which returns a snapshot of the LVB (glimpse)

- add an AST which returns a snapshot of the LVB (glimpse)
- add llite and LOV code to respond to glimpse ASTs with the
  stripe-adjusted size of the inode
- add a policy function on the filter; this policy either grants a
[0,-1] PR lock, if no conflicts, or performs a glimpse and returns
that LVB
- send LVB in completion AST
- add lvb_swabber pointer to ldlm_lock and enqueue functions
- remove never-used parent_lock_handle from enqueue functions
- ldlm_intent_policy renamed to mds_intent_policy
- filter_lvbo_update can now update LVB from the network message or
  disk inode, as required