network: Add virtio-net dependencies

The newly added virtio-net implementation needs to interact with TAP
interfaces and MAC addresses, which is the reason why it is easier
to rely on existing packages net_util and net_gen.

One more thing, both net_util and net_gen could be trimmed down,
based on using only the things we need from cloud-hypervisor.

Both net_util, net_gen and sys_util are based on Firecracker
commit d4a89cdc0bd2867f821e3678328dabad6dd8b767.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>

net_gen/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "net_gen"
+version = "0.1.0"
+authors = ["The Chromium OS Authors"]
+
+[dependencies]
+vmm-sys-util = { git = "https://github.com/sameo/vmm-sys-util" }