Gate z_mergetoaddress as an experimental feature

src/init.cpp

@@ -793,6 +793,8 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         }
         else if (mapArgs.count("-paymentdisclosure")) {
             return InitError(_("Payment disclosure requires -experimentalfeatures."));
+        } else if (mapArgs.count("-zmergetoaddress")) {
+            return InitError(_("RPC method z_mergetoaddress requires -experimentalfeatures."));
         }
     }