- new BR pkgconfig(libnftnl) to fix nftables support

- update to 2.0.19
Fix minor IPVS features support. Extend BFD to support more than
one BFD instance with a neighnour. Extend nftable support. Script
timeout extension. Properly filter IGMP/MLD packets on VMAC
interface. Refer to ChangeLog for more infos.
https://keepalived.org/changelog.html
- changes from 2.0.18
Add support to IPVS new GUE tunnel type. New feature 'weight
reverse' available in all trackers. Resolve all outstanding
coverity issues. Some fixes and performance extensions. Refer to
ChangeLog for more infos.
https://keepalived.org/changelog.html