implement evtchn support

xenevtchn/examples/simple.rs

@@ -0,0 +1,10 @@
+use xenevtchn::{EventChannel, EventChannelError};
+
+fn main() -> Result<(), EventChannelError> {
+    let mut channel = EventChannel::open()?;
+    println!("Channel opened.");
+    let port = channel.bind_unbound_port(1)?;
+    println!("port: {}", port);
+    channel.unbind(port)?;
+    Ok(())
+}