tools: virtio: introduce vhost_net_test

introduce vhost_net_test for both vhost_net tx and rx basing
on virtio_test to test vhost_net changing in the kernel.

Steps for vhost_net tx testing:
1. Prepare a out buf.
2. Kick the vhost_net to do tx processing.
3. Do the receiving in the tun side.
4. verify the data received by tun is correct.

Steps for vhost_net rx testing:
1. Prepare a in buf.
2. Do the sending in the tun side.
3. Kick the vhost_net to do rx processing.
4. verify the data received by vhost_net is correct.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/virtio: Ignore virtio-trace/trace-agent

since commit 108fc82596e3("tools: Add guest trace agent as a user tool")
introduce virtio-trace/trace-agent, it should be ignored in the git tree.

Signed-off-by: Rong Tao <rongtao@cestc.cn>
Message-Id: <tencent_52B2BC2F47540A5FEB46E710BD0C8485B409@qq.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

.gitignore: add SPDX License Identifier

Add SPDX License Identifier to all .gitignore files.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

virtio tools: add .gitignore

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>