Remove carp_seroute() it no longer does anything useful but mess with

Remove carp_seroute() it no longer does anything useful but mess with
your IPv4 routes.

mcbride@ says that this function has been introduced in order to be able
to reach the MASTER node from a BACKUP node using the CARP address. The
reasons are:

1) For troubleshooting, so I can ping or otherwise monitor the MASTER
host.

2) In some cases it's undesirable (or even not possible) to run
services on other IP addresses. For example, services that only allow
you to configure 1 listening IP, or services where you wish to avoid
users connecting to anything but the MASTER server.

Sadly this function becames a horrible hack.  So if somebody thinks the
reasons explained before justify such logic, feel free to submit a
correct diff.

ok bluhm@, henning@, mikeb@