Merge remote-tracking branch 'remotes/jasowang/tags/net-pull-request' into staging

Merge remote-tracking branch 'remotes/jasowang/tags/net-pull-request' into staging

# gpg: Signature made Wed 15 Jul 2020 14:49:07 BST
# gpg:                using RSA key EF04965B398D6211
# gpg: Good signature from "Jason Wang (Jason Wang on RedHat) <jasowang@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 215D 46F4 8246 689E C77F  3562 EF04 965B 398D 6211

* remotes/jasowang/tags/net-pull-request:
  ftgmac100: fix dblac write test
  net: detect errors from probing vnet hdr flag for TAP devices
  net: check if the file descriptor is valid before using it
  qemu-options.hx: Clean up and fix typo for colo-compare
  net/colo-compare.c: Expose compare "max_queue_size" to users
  hw/net: Added CSO for IPv6
  virtio-net: fix removal of failover device

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>