block_util: Add utilities to support io_uring

Creates a dedicated function relying on io_uring crate to execute
io_uring specific requests.

Also creates a function for checking io_uring support on the host.

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

Cargo.lock

@@ -148,6 +148,8 @@ dependencies = [
 name = "block_util"
 version = "0.1.0"
 dependencies = [
+ "io-uring",
+ "libc",
  "log 0.4.11",
  "serde",
  "serde_derive",
@@ -155,6 +157,7 @@ dependencies = [
  "virtio-bindings",
  "vm-memory",
  "vm-virtio",
+ "vmm-sys-util",
 ]
 
 [[package]]
@@ -485,6 +488,15 @@ dependencies = [
  "unicode-normalization",
 ]
 
+[[package]]
+name = "io-uring"
+version = "0.3.5"
+source = "git+https://github.com/tokio-rs/io-uring.git?branch=0.4#c00d968b038263a02a72d6510edaf438b0c7b4f3"
+dependencies = [
+ "bitflags 1.2.1",
+ "libc",
+]
+
 [[package]]
 name = "ipnetwork"
 version = "0.16.0"