Only add the importNative primop if the allow-arbitrary-code-during-evaluation option is true (default false)

src/libstore/globals.hh

@@ -200,6 +200,9 @@ struct Settings {
     /* A list of URL prefixes that can return Nix build logs. */
     Strings logServers;
 
+    /* Whether the importNative primop should be enabled */
+    bool enableImportNative;
+
 private:
     SettingsMap settings, overrides;