sample.c:(.text+0x92): undefined reference to `cv::imread(std::string const&, int)' sample.c:(.text+0x12a): undefined reference to `cv::namedWindow(std::string const&, int)' sample.c:(.text+0x15b): undefined reference to `cv::_InputArray::_InputArray(cv::Mat const&)' sample.c:(.text+0x19b): undefined reference to `cv::imshow(std::string const&, cv::_InputArray const&)' sample.c:(.text+0x1c3): undefined reference to `cv::waitKey(int)'