use TESTS_SUBDIRS for kern instead of SUBDIRS. I don't think it
makes a difference in this case, but TESTS_SUBDIRS is generally
correct for subdirectories that contain tests.
Sponsored by: Spectra Logic
MFC after: 5 days
X-MFC-With: r261133
were a little broken and not automatable, with unix_seqpacket_test.
It's coverage is a superset of the old tests and it uses ATF. It
includes test cases for bugs kern/185813 and kern/185812.
PR: kern/185812
PR: kern/185813
Sponsored by: Spectra Logic
MFC after: 2 weeks