Qutex: currOwner should use registered sh_ptr to Lockvoker

This ensures that the Lockvoker object we access from currOwner
remains valid past the lifetime of the Lockvoker object that
gets copied and invoked by boost::asio

include/qutex.h

@@ -90,13 +90,14 @@ public:
 	void release();
 
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
-	LockerAndInvokerBase* getCurrOwner() const { return currOwner; }
+	std::shared_ptr<LockerAndInvokerBase> getCurrOwner() const
+		{ return currOwner; }
 #endif
 
 public:
 #ifdef CONFIG_ENABLE_DEBUG_LOCKS
 	std::string name;
-	LockerAndInvokerBase* currOwner;
+	std::shared_ptr<LockerAndInvokerBase> currOwner;
 #endif
 	SpinLock lock;
 	LockerAndInvokerBase::List queue;