Fix signature of notifyFrameLost() and add additional assert

src/Limelight-internal.h

@@ -98,7 +98,7 @@ void destroyVideoDepacketizer(void);
 void queueRtpPacket(PRTPV_QUEUE_ENTRY queueEntry);
 void stopVideoDepacketizer(void);
 void requestDecoderRefresh(void);
-void notifyFrameLost(int frameNumber);
+void notifyFrameLost(unsigned int frameNumber);
 
 void initializeVideoStream(void);
 void destroyVideoStream(void);