tipc: Ensure network address change doesn't impact rejected message

Revises handling of a rejected message to ensure that a locally
originated message is returned properly even if the node's network
address is changed in mid-operation. The routine now treats the
default node address of <0.0.0> as an alias for "this node" when
determining where to send a returned message.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>