[PATCH int-new] IPv6 ECMP support fixes for linux

[Mikhail Sennikovskii]

Hello Fellows,

as mentioned in my previous mail, here is a patch 
for IPv6 ECMP support against the int-new branch, for BIRD 2.
The only difference between the master and int-new patches
is that the current (int-new) one uses the rtable.addr_type 
to determine the IPv6-style behavior,
instead of placing it under IPV6 ifdef.

Thanks,
Mikhail