MFC r262133

test_eagain_*_* should've been using nonblocking sockets instead of blocking
sockets.  The error was not exposed as long as the kernel suffered from PR
kern/185812.  Now corrected, these tests pass on DragonFlyBSD 3.6.0.

tests/sys/kern/unix_seqpacket_test.c

@@ -136,7 +136,7 @@ test_eagain(size_t sndbufsize, size_t rcvbufsize)
 	ssize_t ssize, rsize;
 
 	/* setup the socket pair */
-	do_socketpair(sv);
+	do_socketpair_nonblocking(sv);
 	/* Setup the buffers */
 	ATF_REQUIRE_EQ(0, setsockopt(sv[0], SOL_SOCKET, SO_SNDBUF, &sndbufsize,
 	    sizeof(sndbufsize)));