Add vpnkit back to binary targets
This was removed after refactoring the Dockerfile in
@@ -338,6 +338,7 @@ COPY --from=runc /build/ /usr/local/bin/
COPY --from=containerd /build/ /usr/local/bin/
COPY --from=rootlesskit /build/ /usr/local/bin/
COPY --from=proxy /build/ /usr/local/bin/
+COPY --from=vpnkit /vpnkit /usr/local/bin/vpnkit.x86_64
WORKDIR /go/src/github.com/docker/docker
FROM binary-base AS build-binary
