Interleave jumping into chains with filtering rules in 'root' table

Interleave jumping into chains with filtering rules in 'root' table

The previous patch extends the priority of filtering rules into negative
numbers. We now use this possibility to interleave the jumping into
chains with filtering rules to for example create the 'root' table of
an interface with the following sequence of rules:

Bridge chain: libvirt-I-vnet0, entries: 6, policy: ACCEPT
-p IPv4 -j I-vnet0-ipv4
-p ARP -j I-vnet0-arp
-p ARP -j ACCEPT
-p 0x8035 -j I-vnet0-rarp
-p 0x835 -j ACCEPT
-j DROP

The '-p ARP -j ACCEPT' rule now appears between the jumps.
Since the 'arp' chain has been assigned priority -700 and the 'rarp'
chain -600, the above ordering can now be achieved with the following
rule:

  <rule action='accept' direction='out' priority='-650'>
    <mac protocolid='arp'/>
  </rule>

This patch now sorts the commands generating the above shown jumps into
chains and interleaves their execution with those for generating rules.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>