vhost_rs: Copy vhost crate from jiangliu/v1

In order to avoid cloud-hypervisor to rely on a pending PR for the empty
crate "vhost", this commit temporarily copies the content of the crate
based on branch jiangliu/v1 18b5081d9199c76eca49da1971c9d1a65e53e5ff.

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

vhost_rs/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "vhost_rs"
+version = "0.1.0"
+authors = ["Liu Jiang <gerry@linux.alibaba.com>"]
+repository = "https://github.com/rust-vmm/vhost"
+license = "Apache-2.0 or BSD-3-Clause"
+
+[features]
+default = []
+vhost-vsock = []
+vhost-kern = ["vm-memory"]
+vhost-user-master = []
+vhost-user-slave = []
+
+[dependencies]
+bitflags = ">=1.0.1"
+libc = ">=0.2.39"
+vmm-sys-util = { git = "https://github.com/rust-vmm/vmm-sys-util" }
+
+[dependencies.vm-memory]
+git = "https://github.com/rust-vmm/vm-memory"
+optional = true
+
+[dev-dependencies]
+tempfile = "3.0.5"