add x86_64  xz reinstall

add option '--x64' for release 'x86' and 'x86_64'
support *.xz package
add command 'reinstall'
@s7726 apt-cyg does not have a default mirror anymore, it just reads from `/etc/setup/setup.rc`. This patch is old

[`apt-cyg#L84-L89`](http://github.com/transcode-open/apt-cyg/blob/73702ab/apt-cyg#L84-L89)