[tlbuild] wget&xz

[Karl Berry]

There have been new releases of wget and xz since last year, so we
should update.
  http://tukaani.org/xz/xz-5.2.2.tar.xz
  ftp://ftp.gnu.org/gnu/wget/wget-1.17.1.tar.xz

The platforms where we distribute wget are:
  wget.amd64-freebsd
  wget.amd64-netbsd
  wget.exe
  wget.i386-freebsd
  wget.i386-netbsd
  wget.i386-solaris
  wget.sparc-solaris
  wget.universal-darwin
  wget.x86_64-darwin
  wget.x86_64-solaris

(Everyone needs xz.)

Thanks,
Karl