Add push_into_stack_multi fastpath to Variadic

Author: khvzak

src/multi.rs

@@ -297,6 +297,15 @@ impl<T: IntoLua> IntoLuaMulti for Variadic<T> {
     fn into_lua_multi(self, lua: &Lua) -> Result<MultiValue> {
         MultiValue::from_lua_iter(lua, self)
     }
+
+    unsafe fn push_into_stack_multi(self, lua: &RawLua) -> Result<c_int> {
+        let nresults = self.len() as i32;
+        check_stack(lua.state(), nresults + 1)?;
+        for value in self.0 {
+            value.push_into_stack(lua)?;
+        }
+        Ok(nresults)
+    }
 }
 
 impl<T: FromLua> FromLuaMulti for Variadic<T> {