xz needs aclocal/automake 1.14 which I don't have on Debian/wheezy.
I leave this for Peter or someone else.
xz should not require autoanything, all the dependencies should be up to
date. I'm baffled.
Can you try downloading the original sources from
http://tukaani.org/xz/xz-5.0.5.tar.gz and see if that is better?
Maybe I messed up the commit.
karl