Instead of having one function for each possible key in lxc.conf which
doesn't really scale and requires an API update for every new key,
switch to a generic lxc_get_global_config_item() function which takes a
key name as argument.
Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>