fuzz: Add fuzzer for virtio-net

To synthesize the interactions between the virtio-net device and the tap
interface, the fuzzer utilizes a pair of unix domain sockets: one socket
(e.g. the dummy tap frontend) is used to construct the 'net_util::Tap'
instance for creating a virtio-net device; the other socket (e.g. the
dummy tap backend) is used in a epoll loop for handling the tx and rx
requests from the virtio-net device.

Signed-off-by: Bo Chen <chen.bo@intel.com>

fuzz/Cargo.lock

@@ -170,6 +170,7 @@ dependencies = [
  "libc",
  "libfuzzer-sys",
  "micro_http",
+ "net_util",
  "once_cell",
  "qcow",
  "seccompiler",