KRT: Fix IPv6 ECMP handling with Linux 4.11+

Starting from Linux 4.11, IPv6 ECMP routes are now notified using
RTA_MULTIPATH, like IPv4 ones. The patch adds support for RTA_MULTIPATH
parsing for IPv6 routes. This also enables to parse ECMP alien routes
correctly.

Thanks to Vincent Bernat for the original patch.
49 jobs from master in 8 minutes and 46 seconds (queued for 1 minute and 12 seconds)
Status Job ID Name Coverage
  Image
passed #44897
dind allowed to fail
docker_centos-6-amd64

00:00:45

passed #44898
dind allowed to fail
docker_centos-7-amd64

00:00:43

passed #44887
dind allowed to fail
docker_debian-7-amd64

00:00:38

passed #44891
dind allowed to fail
docker_debian-7-i386

00:00:38

passed #44888
dind allowed to fail
docker_debian-8-amd64

00:00:40

passed #44892
dind allowed to fail
docker_debian-8-i386

00:00:32

passed #44889
dind allowed to fail
docker_debian-9-amd64

00:00:36

passed #44893
dind allowed to fail
docker_debian-9-i386

00:00:32

passed #44890
dind allowed to fail
docker_debian-testing-amd64

00:00:40

passed #44894
dind allowed to fail
docker_debian-testing-i386

00:00:28

passed #44895
dind allowed to fail
docker_fedora-25-amd64

00:00:48

passed #44896
dind allowed to fail
docker_fedora-26-amd64

00:00:38

passed #44899
dind allowed to fail
docker_opensuse-42_3-amd64

00:00:35

passed #44900
dind allowed to fail
docker_ubuntu-14_04-amd64

00:00:34

passed #44901
dind allowed to fail
docker_ubuntu-16_04-amd64

00:00:27

 
  Build
passed #44914
docker linux amd64
build-centos-6-amd64

00:01:02

passed #44915
docker linux amd64
build-centos-6-amd64-v6

00:01:03

passed #44916
docker linux amd64
build-centos-7-amd64

00:01:06

passed #44917
docker linux amd64
build-centos-7-amd64-v6

00:01:07

passed #44902
docker linux amd64
build-debian-7-amd64

00:01:05

passed #44906
docker linux amd64
build-debian-7-amd64-v6

00:01:32

passed #44924
docker linux amd64
build-debian-7-i386

00:01:09

passed #44925
docker linux amd64
build-debian-7-i386-v6

00:01:09

passed #44903
docker linux amd64
build-debian-8-amd64

00:01:04

passed #44907
docker linux amd64
build-debian-8-amd64-v6

00:01:27

passed #44926
docker linux amd64
build-debian-8-i386

00:01:19

passed #44927
docker linux amd64
build-debian-8-i386-v6

00:01:25

passed #44904
docker linux amd64
build-debian-9-amd64

00:01:10

passed #44908
docker linux amd64
build-debian-9-amd64-v6

00:01:36

passed #44928
docker linux amd64
build-debian-9-i386

00:01:26

passed #44929
docker linux amd64
build-debian-9-i386-v6

00:01:26

passed #44905
docker linux amd64
build-debian-testing-amd64

00:01:19

passed #44909
docker linux amd64
build-debian-testing-amd64-v6

00:01:27

passed #44930
docker linux amd64
build-debian-testing-i386

00:01:20

passed #44931
docker linux amd64
build-debian-testing-i386-v6

00:01:21

passed #44910
docker linux amd64
build-fedora-25-amd64

00:01:20

passed #44911
docker linux amd64
build-fedora-25-amd64-v6

00:01:24

passed #44912
docker linux amd64
build-fedora-26-amd64

00:01:11

passed #44913
docker linux amd64
build-fedora-26-amd64-v6

00:01:10

passed #44932
freebsd amd64
build-freebsd-11-amd64

00:04:33

passed #44933
freebsd amd64
build-freebsd-11-amd64-v6

00:04:34

passed #44934
freebsd i386
build-freebsd-11-i386

00:04:38

passed #44935
freebsd i386
build-freebsd-i386-v6

00:04:40

passed #44918
docker linux amd64
build-opensuse-42_3-amd64

00:01:05

passed #44919
docker linux amd64
build-opensuse-42_3-amd64-v6

00:01:07

passed #44920
docker linux amd64
build-ubuntu-14_04-amd64

00:01:11

passed #44921
docker linux amd64
build-ubuntu-14_04-amd64-v6

00:01:15

passed #44922
docker linux amd64
build-ubuntu-16_04-amd64

00:01:07

passed #44923
docker linux amd64
build-ubuntu-16_04-amd64-v6

00:01:10