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/store-api.hh

@@ -254,6 +254,10 @@ public:
     /* Optimise the disk space usage of the Nix store by hard-linking files
        with the same contents. */
     virtual void optimiseStore() = 0;
+
+    /* Check the integrity of the Nix store.  Returns true if errors
+       remain. */
+    virtual bool verifyStore(bool checkContents, bool repair) = 0;
 };