Add rust to go dynamic library example.

rust-to-go-dynamic/src/double.go

@@ -0,0 +1,10 @@
+package main
+
+import "C"
+
+//export DoubleInput
+func DoubleInput(input int32) int32 {
+  return input * 2
+}
+
+func main() {}

rust-to-go-dynamic/src/main.rs

@@ -0,0 +1,12 @@
+extern crate libc;
+
+#[link(name = "double_input")]
+extern {
+    fn DoubleInput(input: libc::c_int) -> libc::c_int;
+}
+
+fn main() {
+    let input = 2;
+    let output = unsafe { DoubleInput(input) };
+    println!("{} * 2 = {}", input, output);
+}