Minor fix for Web Cam on OpenCV 3.x

AlexeyAB

2018-04-06 1b1221ace5f49b5b464cf7f4ff89f31cf03d3da1

 src/demo.c

@@ -24,6 +24,7 @@
#ifndef CV_VERSION_EPOCH
#include "opencv2/videoio/videoio_c.h"
#endif
#include "http_stream.h"
image get_image_from_stream(CvCapture *cap);

static char **demo_names;