Add rust toolchains

Signed-off-by: Ravago Jones <ravagojones@gmail.com>
Change-Id: I5f36ff152b01bbb628dea45175294cf7f52bb15f
diff --git a/build_tests/rust_hello.rs b/build_tests/rust_hello.rs
new file mode 100644
index 0000000..6c6bf9f
--- /dev/null
+++ b/build_tests/rust_hello.rs
@@ -0,0 +1,21 @@
+extern crate hello_lib;
+
+extern "C" {
+    fn sqrt(x: f64) -> f64;
+}
+
+fn main() {
+  let hello = hello_lib::Greeter::new("Hello");
+  println!("{},\n{}", hello.greet("world"), hello.greet("bazel"));
+
+  let mut numbers = Vec::new();
+  for i in 1..=10 {
+      numbers.push(i);
+  }
+  println!("{:?}", numbers);
+
+  let words = vec!["foo", "bar", "baz"];
+  println!("{:?}", words);
+
+  println!("sqrt(4) = {}", unsafe { sqrt(4.0) });
+}