kbuild: Mark that the packages generated conform to Standards-Version 3.8.4

The packages generated by the builddeb script conform to the Debian
Policy version 3.8.4. Make this explicit in the generated packages.

Signed-off-by: Rogério Brito <rbrito@ime.usp.br>
Signed-off-by: Michal Marek <mmarek@suse.cz>