fix another link-resolver related crash (non auto url unshort-related)

src/messages/MessageBuilder.cpp

@@ -196,6 +196,11 @@ MessagePtr MessageBuilder::release()
     return ptr;
 }
 
+std::weak_ptr<Message> MessageBuilder::weakOf()
+{
+    return this->message_;
+}
+
 void MessageBuilder::append(std::unique_ptr<MessageElement> element)
 {
     this->message().elements.push_back(std::move(element));

src/messages/MessageBuilder.hpp

@@ -43,6 +43,7 @@ public:
     Message *operator->();
     Message &message();
     MessagePtr release();
+    std::weak_ptr<Message> weakOf();
 
     void append(std::unique_ptr<MessageElement> element);
     QString matchLink(const QString &string);