Add Rust target

spec/test_start_rule_tree.rs

@@ -0,0 +1,12 @@
+use testparser::*;
+
+fn main() {
+    let mut context = p_context_new(b"hi");
+    assert_eq!(P_SUCCESS, p_parse(&mut context));
+    {
+        let top = p_result(&context);
+        assert!(top.pToken().valid());
+        assert_eq!(TOKEN_hi, top.pToken().token());
+    }
+    p_context_delete(context);
+}