update indigo

* submodules/indigo 1a2b943...216a076 (2):
  > Merge into master from pull request #158: OFConnectionManager: add notifications for barriers (https://github.com/floodlight/indigo/pull/158)
  > Merge into master from pull request #157: Add generation ID to the connection ID, and pause reading messages during long-running tasks (https://github.com/floodlight/indigo/pull/157)
update loxigen-artifacts

* submodules/loxigen-artifacts 835e6c4...8619d52 (3):
  > Artifacts from https://github.com/floodlight/loxigen/compare/1dcdc363b51be6f0c8e02648bf5dbbc0b2b2708c...e9d105578e13db5fa6c52f0b8c7b4d80f328b31a
  > Artifacts from https://github.com/floodlight/loxigen/compare/201b2d72df2f8d39d9e87bebdf5e348772e26716...1dcdc363b51be6f0c8e02648bf5dbbc0b2b2708c
  > Artifacts from https://github.com/floodlight/loxigen/compare/d521400167a9a8e014afffed95952e3412f85007...201b2d72df2f8d39d9e87bebdf5e348772e26716
OVSDriver: defer kflow revalidation until a barrier request

The goal is to speed up adding flowtable entries when there are many kernel
flows.
update indigo

* submodules/indigo 216a076...655d3cd (2):
  > Merge into master from pull request #160: OFConnectionManager: add assertions for clang static analyzer (https://github.com/floodlight/indigo/pull/160)
  > Merge into master from pull request #159: Optimize flowtable iteration (https://github.com/floodlight/indigo/pull/159)
Merge into master from pull request #192:
OVSDriver: defer kflow revalidation until a barrier request (https://github.com/floodlight/ivs/pull/192)