Prevent ObjectLock from being copied

Copying an ObjectLock results in the underlying mutex being unlocked too often.
There's also no good reason for copying a scoped locking class (if at all, it
should be moved).

lib/base/objectlock.hpp

@@ -17,6 +17,9 @@ public:
 	ObjectLock(const Object::Ptr& object);
 	ObjectLock(const Object *object);
 
+	ObjectLock(const ObjectLock&) = delete;
+	ObjectLock& operator=(const ObjectLock&) = delete;
+
 	~ObjectLock();
 
 	void Lock();