Revert "GetSeedDataDirs: allow TEST_DATA_DIRS to be -D defined (AOMed…

…iaCodec#2162)"

This reverts commit d369ffb.

This change was meant to allow the fuzz tests to be run by Chrome's
ClusterFuzz, but the source tree is unavailable in the fuzzer
environment and there is no way to copy the data currently. Adding the
ability for the latter was also discouraged by the security/clusterfuzz
team.

tests/gtest/avif_fuzztest_helpers.cc

@@ -223,22 +223,9 @@ ::testing::Environment* SetEnv(const char* name, const char* value) {
 
 //------------------------------------------------------------------------------
 
-#ifdef TEST_DATA_DIRS
-// Helper macros to ensure TEST_DATA_DIRS is a quoted string.
-// NOTE: TEST_DATA_DIRS must NOT be a quoted string before stringification
-// otherwise it will be quoted twice, resulting in the use of an incorrect path.
-#define AVIF_TO_STRING(S) #S
-#define AVIF_STRINGIFY(S) AVIF_TO_STRING(S)
-#endif
-
 std::vector<std::string> GetSeedDataDirs() {
   const char* var = std::getenv("TEST_DATA_DIRS");
   std::vector<std::string> res;
-#ifdef TEST_DATA_DIRS
-  if (var == nullptr) {
-    var = AVIF_STRINGIFY(TEST_DATA_DIRS);
-  }
-#endif
   if (var == nullptr || *var == 0) return res;
   const char* var_start = var;
   while (true) {
@@ -252,9 +239,6 @@ std::vector<std::string> GetSeedDataDirs() {
   return res;
 }
 
-#undef AVIF_STRINGIFY
-#undef AVIF_TO_STRING
-
 std::vector<std::string> GetTestImagesContents(
     size_t max_file_size, const std::vector<avifAppFileFormat>& image_formats) {
   // Use an environment variable to get the test data directory because