Add PACKAGE fields to usr.sbin/extattr/tests/Makefile

usr.sbin/extattr/tests/Makefile
Add boiler plate required by 298107 but omitted by 298483. These
two changes passed through CR in parallel. I think this should get
the full test suite running in Jenkins again.

MFC after: 22 days
X-MFC-with: 298483
Sponsored by: Spectra Logic Corp