fix Misc test failures

The Misc test was failing when run as "make input=Misc run" since
test-flags did not include $(build)/extra-dir in the class library,
leading the ClassLoader.getResources test to fail.

Also, the UnknownHostException test was not reliable -- some ISPs
(mine included) return DNS matches for bogus hostnames, defaulting to
the IP address of a webserver intended to help users with name
resolution problems.  That's dumb, I know, but I'm guessing I'm not
the only person with a dumb ISP, and it seems better to just remove
the test than make people think Avian is broken when it's really just
their DNS server that's broken.