- Don't check if the list is empty needlessly

- Don't check if the list is empty needlessly
- Don't free structures before calling load_config(), because load_config()
  already does it
- Use the existing functions for freeing the minivm structures instead of
  replicating the code
(issue #9846, patch from eliel)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@66772 65c4cc65-6c06-0410-ace0-fbb531ad65f3