tipc: Ensure network address change doesn't impact local connections

Revises routines that deal with connections between two ports on
the same node to ensure the connection is not impacted if the node's
network address is changed in mid-operation. The routines now treat
the default node address of <0.0.0> as an alias for "this node" in
the following situations:

1) Incoming messages destined to a connected port now handle the alias
properly when validating that the message was sent by the expected
peer port, ensuring that the message will be accepted regardless of
whether it specifies the node's old network address or it's current one.

2) The code which completes connection establishment now handles the
alias properly when determining if the peer port is on the same node
as the connected port.

An added benefit of addressing issue 1) is that some peer port
validation code has been relocated to TIPC's socket subsystem, which
means that validation is no longer done twice when a message is
sent to a non-socket port (such as TIPC's configuration service or
network topology service).

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

net/tipc/port.h

@@ -201,6 +201,7 @@ int tipc_shutdown(u32 ref);
  * The following routines require that the port be locked on entry
  */
 int tipc_disconnect_port(struct tipc_port *tp_ptr);
+int tipc_port_peer_msg(struct tipc_port *p_ptr, struct tipc_msg *msg);
 
 /*
  * TIPC messaging routines