Make prim_exec and prim_importNative available to plugins

src/libexpr/primops.hh

@@ -15,4 +15,12 @@ struct RegisterPrimOp
     RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun);
 };
 
+/* These primops are disabled without enableNativeCode, but plugins
+   may wish to use them in limited contexts without globally enabling
+   them. */
+/* Load a ValueInitializer from a DSO and return whatever it initializes */
+void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value & v);
+/* Execute a program and parse its output */
+void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v);
+
 }