Fixed cmake for VideoStreaming library

src/VideoStreaming/CMakeLists.txt

 set(EXTRA_LIBRARIES)
 
 if (GST_FOUND)
-	include_directories(
-		gstqtvideosink/utils/
-	)
-
-	set(EXTRA_SRC
-		gstqtvideosink/delegates/basedelegate.cpp
-		gstqtvideosink/delegates/qtquick2videosinkdelegate.cpp
-		gstqtvideosink/delegates/qtvideosinkdelegate.cpp
-		gstqtvideosink/delegates/qwidgetvideosinkdelegate.cpp
-		gstqtvideosink/gstqtglvideosink.cpp
-		gstqtvideosink/gstqtglvideosinkbase.cpp
-		gstqtvideosink/gstqtquick2videosink.cpp
-		gstqtvideosink/gstqtvideosink.cpp
-		gstqtvideosink/gstqtvideosinkbase.cpp
-		gstqtvideosink/gstqtvideosinkplugin.cpp
-		gstqtvideosink/gstqwidgetvideosink.cpp
-		gstqtvideosink/gstqtvideosinkmarshal.c
-		gstqtvideosink/painters/genericsurfacepainter.cpp
-		gstqtvideosink/painters/openglsurfacepainter.cpp
-		gstqtvideosink/painters/videomaterial.cpp
-		gstqtvideosink/painters/videonode.cpp
-		gstqtvideosink/utils/bufferformat.cpp
-		gstqtvideosink/utils/utils.cpp
-	)
 	set(EXTRA_LIBRARIES ${GST_LIBRARIES})
 endif()
 
 add_library(VideoStreaming
-	VideoItem.cc
 	VideoReceiver.cc
 	VideoStreaming.cc
-	VideoSurface.cc
 	SubtitleWriter.cc
-	${EXTRA_SRC}
+  GLVideoItemStub.cc
 )
 
 target_link_libraries(VideoStreaming