6633549 (dc) Include-mode filtering of IPv6 sources does not block datagrams on Linux

[Alan Bateman]

This is one I tracked down a long time ago but didn't push the changes 
for some reason. On Linux we have disabled support for include-mode 
multicasting with IPv6 addresses (this is allowed by the spec). The 
original issue was because the values for 
MCAST_{JOIN,LEAVE}_SOURCE_GROUP were incorrect, an issue that only 
exists when compiling on older systems that don't have the definitions 
in the include files.

The fix is simply to get rid of the definitions and change joinOrDrop6 
so that it now supports include-mode filtering.  I've also updated one 
of the tests to assert that UOE cannot be thrown on Linux.

The webrev with the changes is here:

http://cr.openjdk.java.net/~alanb/6633549/webrev/

-Alan