avoid dm_save() recursions (FIXME FIXME FIXME)
avoid dm_save() recursions (FIXME FIXME FIXME)

* The sync wrappers around server-to-client requests recurse the event loop.
  Since the SAVE request will include fetching the interfaces state
  (calls rpc_get_interface_state()), the SAVE request could be in certain corner cases
  executed again, resulting in a deadlock because of the non-recursive mutex lock.
* This is only a temporary workaround.
  The event loop recursion itself is broken by design.
  For most server-to-client requests, it could be easily avoided.
  Avoiding event loop recusion in rpc_get_interface_state() would require significant
  refactoring, though.
  It will be easier to reintegrate the RPC implementation (e.g. from mand-metropolisd)
  back into mand - the implementation is OS agnostic, so there is no real reason to have
  this as a RPC.

metratec/mand,metratec/mand,metratec/mand