Use the standard .yuv and .rgb file extensions when saving the decoded jpeg outputs (#34)

* Use the standard .yuv and .rgb file extensions when saving the decoded jpeg outputs

* modify the file description for saving

samples/jpegDecodeMultiThreads/jpegdecodemultithreads.cpp

@@ -99,7 +99,7 @@ void ThreadFunction(std::vector<std::string>& jpegFiles, RocJpegHandle rocjpeg_h
 
         if (save_images) {
             std::string image_save_path = output_file_path;
-            rocjpeg_util.GetOutputFileExt(decode_params.output_format, base_file_name, widths[0], heights[0], image_save_path);
+            rocjpeg_util.GetOutputFileExt(decode_params.output_format, base_file_name, widths[0], heights[0], subsampling, image_save_path);
             rocjpeg_util.SaveImage(image_save_path, output_image, widths[0], heights[0], subsampling, decode_params.output_format);
         }