MFC r270228:
r270228 (by asomers):

Numerous small fixes, mostly suggested by Coverity.

tests/sys/kern/unix_seqpacket_test.c

• Remove a duplicate error check in mk_pair_of_sockets
• Always close sockets in the success path of ATF test cases. Don't

	  bother with the error paths, because those are mostly assertions
	  anyway.  Most of these socket leaks were reported by Coverity.
	  All of them are harmless, because each ATF test case runs in its
	  own process.

• Fix the len argument to send in shutdown_send and

	  shutdown_send_sigpipe.  The old version was using sizeof a pointer
	  instead of sizeof the char array.  Reported by Coverity.

• Change a few ATF_CHECK to ATF_REQUIRE if the test can't reasonably

	  continue past a failure.

CID: 1229995, 1229991, 1229988, 1229994, 1229989, 1229992
CID: 1229993, 1229990, 1229984, 1229967, 1230005, 1229977
CID: 1229966, 1230004, 1229976