WARNING: we currently crash on unmount after the last phase of runtests.

WARNING: we currently crash on unmount after the last phase of runtests.
Phil and I are going to debug this more tomorrow, but this changeset needed
to land.  I feel bad about this, but not as bad as I'd feel sitting with a
thousand lines of changes in my tree another day! =)

- introduced new-style obd_import structure and spread it thickly across the
  ptlrpc infrastructure.
- merged ptlrpc_prep_req and prep_req2 into one import-taking prep_req function.
- added import for ldlm to use when calling out to client
- send local-export handle info in client_obd_connect, so that said import can
  talk to a proper export during ASTs.
- new unified recovd architecture for client- and server-side recovery.
- much header frottage to hand the export -> ldlm_export_data -> import
  structure nesting.
- commented out cli_sem usage, because clients aren't the right place for that
  any more, and we probably don't need them anyway.
- connection-sharing now requires a matching (nid, uuid) pair, to avoid bogus
  sharing on the one-host, server+client case.
- chain exports on the connection for doing per-connection recovery (soon, I
  swear).
- introduced dozens, if not thousands, of bugs, no doubt.