RFR 8216417: cleanup of IPv6 scope-id handling

[Michael McMahon]

Hi,

Could I get the following change to net/nio reviewed please?

It is a general cleanup of IPv6 scope_id handling which removes
a lot of native code trickery (mostly in Linux) and simplifies the handling
of scope_ids such that:

a) when binding/connecting/sending to a link-local address on the same 
machine,
    it is allowed to use addresses without a scope_id. In this case, we 
check local NetworkInterfaces
    for the correct scope_id to use.

b) when connecting/sending to a remote link-local address, then a 
scope_id must be specified
     at all times.

Scope_ids should be handled consistently between net and NIO and across 
all platforms now.

http://cr.openjdk.java.net/~michaelm/8216417/webrev.2/index.html

Thanks,
Michael