Fail if showing an existing non-showable frame.

Setting the xd->corrupted flag in the show_existing_frame case has no
effects because the corrupted flag won't be checked if no tiles are
decoded. Call aom_internal_error instead.

Add comments to retroactively describe the bitstream conformance
requirements that the code is intended to enforce. The code was
originally added in commit d492901dc6c8e925db122db590670b6933c69779:
https://aomedia-review.googlesource.com/c/aom/+/44323

This CL changed the error codes for two test vectors for
invalid_file_test.cc, so the result files of those two test vectors are
updated with the new error codes.

BUG=aomedia:2282

Change-Id: I6f27af073c9b8289e455f84196c269554f4e844f
diff --git a/test/test_data_util.cmake b/test/test_data_util.cmake
index e497efa..630c161 100644
--- a/test/test_data_util.cmake
+++ b/test/test_data_util.cmake
@@ -537,8 +537,10 @@
               "invalid-oss-fuzz-11477.ivf.res"
               "invalid-oss-fuzz-11479.ivf"
               "invalid-oss-fuzz-11479.ivf.res"
+              "invalid-oss-fuzz-11479.ivf.res.2"
               "invalid-oss-fuzz-11523.ivf"
               "invalid-oss-fuzz-11523.ivf.res"
+              "invalid-oss-fuzz-11523.ivf.res.2"
               "invalid-oss-fuzz-9288.ivf"
               "invalid-oss-fuzz-9288.ivf.res"
               "invalid-oss-fuzz-9463.ivf"