BGP: Better dispatch of incoming connections

Since v2 we have multiple listening BGP sockets, and each BGP protocol
has associated one of them. Use listening socket that accepted the
incoming connection as a key in the dispatch process so only BGP
protocols assocaited with that listening socket can be selected.
This is necesary for proper dispatch when VRFs are used.
32 jobs from int-new in 4 minutes and 45 seconds (queued for 11 seconds)
Status Job ID Name Coverage
  Image
passed #213624
dind allowed to fail
docker_centos-6-amd64

00:00:31

passed #213625
dind allowed to fail
docker_centos-7-amd64

00:00:30

passed #213614
dind allowed to fail
docker_debian-7-amd64

00:00:29

passed #213618
dind allowed to fail
docker_debian-7-i386

00:00:31

passed #213615
dind allowed to fail
docker_debian-8-amd64

00:00:30

passed #213619
dind allowed to fail
docker_debian-8-i386

00:00:32

passed #213616
dind allowed to fail
docker_debian-9-amd64

00:00:30

passed #213620
dind allowed to fail
docker_debian-9-i386

00:00:30

passed #213617
dind allowed to fail
docker_debian-testing-amd64

00:00:31

passed #213621
dind allowed to fail
docker_debian-testing-i386

00:00:32

passed #213622
dind allowed to fail
docker_fedora-25-amd64

00:00:31

passed #213623
dind allowed to fail
docker_fedora-26-amd64

00:00:33

passed #213626
dind allowed to fail
docker_opensuse-42_3-amd64

00:00:31

passed #213627
dind allowed to fail
docker_ubuntu-14_04-amd64

00:00:32

passed #213628
dind allowed to fail
docker_ubuntu-16_04-amd64

00:00:34

 
  Build
passed #213635
docker linux amd64
build-centos-6-amd64

00:01:19

passed #213636
docker linux amd64
build-centos-7-amd64

00:01:03

passed #213629
docker linux amd64
build-debian-7-amd64

00:01:02

passed #213640
docker linux amd64
build-debian-7-i386

00:01:11

passed #213630
docker linux amd64
build-debian-8-amd64

00:01:03

passed #213641
docker linux amd64
build-debian-8-i386

00:01:11

passed #213631
docker linux amd64
build-debian-9-amd64

00:01:06

passed #213642
docker linux amd64
build-debian-9-i386

00:00:59

passed #213632
docker linux amd64
build-debian-testing-amd64

00:01:07

passed #213643
docker linux amd64
build-debian-testing-i386

00:00:54

passed #213633
docker linux amd64
build-fedora-25-amd64

00:01:33

passed #213634
docker linux amd64
build-fedora-26-amd64

00:01:31

passed #213644
freebsd amd64
build-freebsd-11-amd64

00:01:45

passed #213645
freebsd i386
build-freebsd-11-i386

00:01:39

passed #213637
docker linux amd64
build-opensuse-42_3-amd64

00:01:03

passed #213638
docker linux amd64
build-ubuntu-14_04-amd64

00:01:11

passed #213639
docker linux amd64
build-ubuntu-16_04-amd64

00:01:11