Fix assertion failure due to errors in facility block

fac_list is initialized to be empty in facility_init. So if there is any
error with the facility block, it would still be empty. On the other
hand, if the facility block is used, it will be deleted from the list in
log_conf_commit() which would make it glist_null due to the way
glist_del is defined. So the list head may be null or empty!

Signed-off-by: Malahal Naineni <malahal@us.ibm.com>