Regenerate protobuf for 3.5.1
Regenerate protobuf for 3.5.1

Protobuf was updated to version 3.5, in commit 9b981e255e4b3172b54db76e3c96021f981f3e27
and regenerated in 93c3290f31990bf4fe0e01759deea7ac55c4d955, however in 58e42ec9f7f3d241966b1d0f7bc34457888f6aa4
those changes were reverted; possibly due to an older version of protobuf being used.

These are the changes after running `make generate` after installing protobuf 3.5.1

Signed-off-by: Sebastiaan van Stijn <64b2b6d12bfe4baae7dad3d018f8cbf6b0e7a044@gone.nl>

docker/swarmkit,docker/swarmkit,dperny/swarmkit-1,dperny/swarmkit-1