Minor/cosmetic changes:

. on BSD use warn(3) instead of static "socket_error",

	  which is doing the same thing, but poorly;

. use herror(3) instead of "socket_error", when reporting

	  DNS-related problems;

. patch the test-harness to not fail if our own hostname

	  is not resolvable -- this is a sign of misconfiguration,
	  not of the library miscompilation.