lxccontainer: don't lock around getstate and freeze/unfreeze (v2)

Those go through commands.c and are already mutex'ed that way.

Also remove a unmatched container_disk_unlock in lxcapi_create.

Since is_stopped uses getstate which is no longer locked, rename
it to drop the _locked suffix.

And convert save_config to taking the disk lock.  This way the
save_ and load_config are mutexing each other, as they should.

Changelog: May 29:
   Per Dwight's comment, take the lock before opening the config
      FILE *.
   Only take disklock at load and save_config when we're using the
   container's config file, not when read/writing from/to another
   file.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Dwight Engen <dwight.engen@oracle.com>