Reverting "Adds support for reading and writing 10/12-bit y4m" for now because of Mac Build Failure.

This reverts commit 82dc1332af

Change-Id: I824bf42bf47c7df6985c79e451d6af913030d374

test/video_source.h

@@ -50,15 +50,6 @@ static FILE *OpenTestDataFile(const std::string& file_name) {
   return fopen(path_to_source.c_str(), "rb");
 }
 
-static FILE *OpenTestOutFile(const std::string& file_name) {
-  const std::string path_to_source = GetDataPath() + "/" + file_name;
-  return fopen(path_to_source.c_str(), "wb");
-}
-
-static FILE *OpenTempOutFile() {
-  return tmpfile();
-}
-
 // Abstract base class for test video sources, which provide a stream of
 // vpx_image_t images with associated timestamps and duration.
 class VideoSource {