api: convert lxc_wait, lxc_freeze, and lxc_unfreeze

These are the last of the simpler conversions.  Start, execute,
kill, info and attach remain to be done.

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