Revert "dnsmasq: change 'add_local_hostname' to use dnsmasq '--interface-name'"

Revert "dnsmasq: change 'add_local_hostname' to use dnsmasq '--interface-name'"

This causes problem when a FQDN is configured in /etc/config/system. The
domain name will appear twice in reverse DNS.

Next to that, there seems to be a bug in dnsmasq. From the manual page:

--interface-name=<name>,<interface>[/4|/6]
Return  a  DNS  record  associating  the  name  with  the primary address
on the given interface. This flag specifies an A or AAAA record for the
given name in the same way as an /etc/hosts line, except that the address
is not constant, but taken from the given interface. The interface may be
followed by "/4" or "/6" to specify  that  only  IPv4  or  IPv6 addresses
of the interface should be used. If the interface is down, not configured
or non-existent, an empty record is returned. The matching PTR record is
also created, mapping the interface address to the name. More than one name
may be associated with an interface address by repeating the flag; in that
case the first instance is used for  the  reverse address-to-name mapping.

It does not just create an A/AAAA record for the primary address, it creates
one for all addresses. And what is worse, it seems to actually resolve to the
non-primary address first. This is quite annoying when you use floating IP
addresses (e.g. VRRP), because when the floating IP is on the other device,
SSH failes due to incorrect entry in the known hosts file.

I know that this is not a common setup, but it would be nice if there was an
option to restore the previous behaviour, rather than just forcing this new
feature on everybody.

Reported-by: Stijn Tintel <stijn@linux-ipv6.be>
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>