vhost: many vhost user ports (backporting to v16.11)

Hi,

in DPDK v17.02-rc2 there is available following patch:

commit: 59317cef249c0b23098543df527b3e360ce9764f

"""
vhost: allow many vhost-user ports
Currently select() is used to monitor file descriptors for vhostuser ports. This limits the number of ports possible to create since the fd number is used as index in the fd_set and we have seen fds > 1023. This patch changes select() to poll(). This way we can keep an packed (pollfd) array for the fds, e.g. as many fds as the size of the array.
Also see:
http://dpdk.org/ml/archives/dev/2016-April/037024.html

"""

I tested this feature with OVS and DPDK v17.02-rc2. I applied also this patch to DPDK v16.11 without any issues and performed the same tests as for v17.02-rc2.
It solves the problem with connecting many VMs to one vSwitch instance (in my tests 70 VMs) with vhost user ports.

Is it possible to backport this feature to DPDK v16.11?

Br,
Robert