Log Message:
graphics/ruby-cairo: update to 1.15.11

Release 1.15.11 (2017-12-14) Kouhei Sutou <kou@cozmixng.org>
============================================================

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

  * Added cairo 1.15.10 support.

    * Added Cairo::SVGUnit

    * Added Cairo::SVGSurface#document_unit

    * Added Cairo::SVGSurface#document_unit=

    * Added Cairo::MIMEType::CCITT_FAX

    * Added Cairo::MIMEType::CCITT_FAX_PARAMS

    * Added Cairo::MIMEType::EPS

    * Added Cairo::MIMEType::EPS_PARAMS

  * test: Updated expected value for cairo 1.15.
    [GitHub#50][Reported by Mamoru TASAKA]

  * Windows: Updated bundled libraries:

    * libpng: 1.6.32 -> 1.6.34

    * libxml2: 2.9.6 -> 2.9.7

    * cairo: 1.15.8 -> 1.15.10

Thanks
------

  * Mamoru TASAKA

Release 1.15.10 (2017-10-15) Kouhei Sutou <kou@cozmixng.org>
============================================================

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

  * Windows: Ensure setting PATH environment variable.

  * Added cairo 1.15.8 support.

  * Windows: Updated bundled libraries:

    * libpng: 1.6.29 -> 1.6.32

    * freetype: 2.9.4 -> 2.9.6

    * fontconfig: 2.12.1 -> 2.12.4

    * cairo: 1.15.4 -> 1.15.8