Add Rust target

spec/test_optional_rule_component.rs

@@ -0,0 +1,9 @@
+use testparser::*;
+
+fn main() {
+    for input in [&b"b"[..], &b"abcd"[..], &b"abdc"[..]] {
+        let mut context = p_context_new(input);
+        assert_eq!(P_SUCCESS, p_parse(&mut context));
+        p_context_delete(context);
+    }
+}