don't support encrypted frames, don't try to decompress it. Decryption
is supposed to be applied before decompression, so currently the decompression
isn't possible.
BUG:112919
git-svn-id: svn://anonsvn.kde.org/home/kde/trunk/kdesupport/taglib@503234 283d02a7-25f6-0310-bc7c-ecb5cbfe19da