[OC-10514] Update keepalived to be IPv6 friendly.

Keepalived 1.1.20 won't manage a IPv6 VIP. Upgrading to 1.2.9 pulls in
a large amount of IPv6 work (1.2.0 1.2.8 and 1.2.9 all contain fixes)

Upgrading to 1.2.9 also appears to obsolete our patches to ntohl; line
968 of vrrp.c looks like our patch.

From the changelog (http://www.keepalived.org/changelog.html), it
looks like there have been updates to the unicast code in 1.2.8 and
1.2.9, which may also obsolete our unicast patch. However this
probably will require testing, and perhaps changes to our
configuration process.

This includes a patch pulled from master to allow it to build on older kernels.
Specifically, centos 5.5 now builds and passes CI (although there's no test 
coverage for keepalived, so take that with a grain of salt.) 

This patch will be obsolete when we upgrade past 1.2.9

@seth @lamont-granquist @sdelano @marcparadise