Log Message:
update ruby-rcairo to 1.12.8.

Release 1.12.8 (2013-12-23) Kouhei Sutou <kou@cozmixng.org>
===========================================================

Fixes
-----

  * Bundled missing libwinpthread-1.dll into gem for Windows.
    [Reported by Masafumi Yokoyama]

Thanks
------

  * Masafumi Yokoyama

Release 1.12.7 (2013-12-23) Kouhei Sutou <kou@cozmixng.org>
===========================================================

Improvements
------------

  * Added paper sizes of ISO B series and JIS B series.
    [Patch by 5.5]
  * Added Windows binary for Ruby 2.1.0.
  * Updated bundled cairo to 1.12.16 from 1.12.14 for Windows.

Fixes
-----

  * Fixed a bug that Cairo::ImageSurface.new(cloned_data, ...)
    changes both the original data and the cloned data.
    [Patch by Naoyuki Hirayama]

Thanks
------

  * 5.5
  * Naoyuki Hirayama