Add a ‘verifyStore’ RPC

Hello!

The patch below adds a ‘verifyStore’ RPC with the same signature as the
current LocalStore::verifyStore method.

Thanks,
Ludo’.

>From aef46c03ca77eb6344f4892672eb6d9d06432041 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Mon, 1 Jun 2015 23:17:10 +0200
Subject: [PATCH] Add a 'verifyStore' remote procedure call.

src/libstore/worker-protocol.hh

@@ -42,7 +42,8 @@ typedef enum {
     wopQueryValidPaths = 31,
     wopQuerySubstitutablePaths = 32,
     wopQueryValidDerivers = 33,
-    wopOptimiseStore = 34
+    wopOptimiseStore = 34,
+    wopVerifyStore = 35
 } WorkerOp;