virDomainBlockPullAll and virDomainBlockPullAbort are handled automatically.
virDomainBlockPull and virDomainBlockPullInfo require manual overrides since
they return a custom type.

* python/generator.py: reenable bindings for this entry point
* python/libvirt-override-api.xml python/libvirt-override.c:
  manual overrides
Signed-off-by: NAdam Litke <agl@us.ibm.com>
Acked-by: NDaniel P. Berrange <berrange@redhat.com>