Update ruby-2.0.0 to rc2

http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-dev/46958

MD5 verified against above

```
cwgem@elixer ~/rvm $ rvm use ruby-2.0.0
Using /home/cwgem/.rvm/gems/ruby-2.0.0-rc2
cwgem@elixer ~/rvm $ ruby --version
ruby 2.0.0dev (2013-02-08 trunk 39161) [x86_64-linux]
```