Check the Buildservice magic files (_link/_service) with xmllint
also check for orphan files when _services are used

When _service mode is disabled or localrun, it is safe
to use file-reference checking..
Merge pull request #5 from dirkmueller/service_sanity

Check packages with _service files as well
- do not complain about temporary directories when running source services (on server esp.)
Support ARM build hosts