[packagekit] Updated backends now crashing

[Anders F Björklund]

I updated some backends to remove the PK_BACKEND_OPTIONS
table, and now it is aborting with an assertion instead.
This happens for those methods that were previously NULL
in the table, and that now are simply unimplemented:

PackageKit-CRITICAL **: pk_backend_simulate_install_packages: assertion `backend->priv->desc->simulate_install_packages != NULL' failed

	g_return_if_fail (PK_IS_BACKEND (backend)); 
	g_return_if_fail (backend->priv->desc->install_packages != NULL);

Should it really be using debugging assertions to check
for those unimplemented methods, or is there something
else that needs to be changed as part of the update ?
Does the pk_backend_get_roles() have to be implemented ?

--anders