Unbreak the build when MK_TESTS != no after r304527

• src.opts.mk should be bsd.own.mk on ^/stable/10
• LIBADD should be DPADD/LDADD on ^/stable/10

Pointyhat to: kib
Reported by: Olivier Pinter <oliver.pinter@hardenedbsd.org>
Sponsored by: EMC / Isilon Storage Division