Fix udp:setpeername("*")

There seems to be a curious difference between MacOS and
Linux and I am not sure if this is documented. When you
break a "connection" on Mac OS, you only eliminate the peer
association, but the local address remains bound. On Linux,
breaking a "connection" eliminates the binding to the local
address. Have you guys ever come accross this?

Another irritating difference is that connect() returns the
error EAFNOSUPPORT on Mac OS. I am going to ignore all
errors when the reason for calling connect() is simply to
break the "connection".

TODO

@@ -1,3 +1,5 @@
+- bizarre default values for getnameinfo should throw error instead!
+
 - document the new bind and connect behavior.
 - shouldn't we instead make the code compatible to Lua 5.2
   without any compat stuff, and use a compatibility layer to