[tlbuild] x86_64-linux builder

[Karl Berry]

    My kernel is a bit older than Manuel Pégourié-Gonnard's, but still fairly
    recent. My system is Mandriva 2009.0 x86_64. I just finished a successful
    build...

Thanks John.  Since Peter Breitenlohner seems to have the least common
denominator x86_64-linux, we're hoping his builds will work for
everyone.  After I check in the binaries (sometime soon, I hope), it'd
be great if you could try them.

Best,
Karl