Reverts llvm commit 42eaf4fe0adef3344adfd9fbccd49f325cb549ef, pointed from
bisect as source of regression that causes liblzma to encode/decode
incorrectly. It's know to affect powerpc64 BE only.
The patch unbreaks FreeBSD powerpc64 installation media, since bsdinstall
cannot uncompress the *.txz files produced by FreeBSD CI (data corruption).
Reported to upstream in: https://bugs.llvm.org/show_bug.cgi?id=51714
MFC after: 2 days