libcamera: timer: Stop timer when it is deleted

If a timer is running while it's deleted it is still register with the
event dispatcher. This causes a segmentation fault when the timer
time-out and its signal is emitted. Fix this my stopping the timer when
it's deleted.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

include/libcamera/timer.h

@@ -17,6 +17,7 @@ class Timer
 {
 public:
 	Timer();
+	~Timer();
 
 	void start(unsigned int msec);
 	void stop();

src/libcamera/timer.cpp

@@ -43,6 +43,11 @@ Timer::Timer()
 {
 }
 
+Timer::~Timer()
+{
+	stop();
+}
+
 /**
  * \brief Start or restart the timer with a timeout of \a msec
  * \param[in] msec The timer duration in milliseconds