Fix GCC 4.7 errors

GCC 4.7.2 fail overriding constructors defined with virtual and default.
Debian build also fails linking  without -lrt.
INT64_C is not defined on Debian with 4.7.2. "ll" should be enough.

Change-Id: Ia779f094ed64fc3b1941429485e81520d017c2f5
Reviewed-on: https://weave-review.googlesource.com/1671
Reviewed-by: Alex Vakulenko <avakulenko@google.com>
diff --git a/src/notification/notification_channel.h b/src/notification/notification_channel.h
index 5fb7993..ef152a8 100644
--- a/src/notification/notification_channel.h
+++ b/src/notification/notification_channel.h
@@ -17,7 +17,7 @@
 
 class NotificationChannel {
  public:
-  virtual ~NotificationChannel() = default;
+  virtual ~NotificationChannel() {}
 
   virtual std::string GetName() const = 0;
   virtual bool IsConnected() const = 0;
diff --git a/src/notification/notification_delegate.h b/src/notification/notification_delegate.h
index 719d76d..263c2f3 100644
--- a/src/notification/notification_delegate.h
+++ b/src/notification/notification_delegate.h
@@ -24,7 +24,7 @@
   virtual void OnDeviceDeleted(const std::string& cloud_id) = 0;
 
  protected:
-  virtual ~NotificationDelegate() = default;
+  virtual ~NotificationDelegate() {}
 };
 
 }  // namespace weave
diff --git a/src/notification/xmpp_channel.h b/src/notification/xmpp_channel.h
index e6185d9..50e84d2 100644
--- a/src/notification/xmpp_channel.h
+++ b/src/notification/xmpp_channel.h
@@ -33,7 +33,7 @@
   virtual void SendMessage(const std::string& message) = 0;
 
  protected:
-  virtual ~XmppChannelInterface() = default;
+  virtual ~XmppChannelInterface() {}
 };
 
 class XmppChannel : public NotificationChannel,
diff --git a/src/notification/xmpp_stream_parser.h b/src/notification/xmpp_stream_parser.h
index 41faaff..b8f5723 100644
--- a/src/notification/xmpp_stream_parser.h
+++ b/src/notification/xmpp_stream_parser.h
@@ -49,7 +49,7 @@
     virtual void OnStanza(std::unique_ptr<XmlNode> stanza) = 0;
 
    protected:
-    virtual ~Delegate() = default;
+    virtual ~Delegate() {}
   };
 
   explicit XmppStreamParser(Delegate* delegate);