Log Message:
Update ruby-pkg-config to 1.2.7.

== 1.2.7 - 2017-08-16

=== Improvements

  * Improved Homebrew repository detection.
    [Reported by Wyatt Kirby]

=== Thanks

  * Wyatt Kirby

== 1.2.6 - 2017-08-13

=== Improvements

  * Improved Homebrew repository detection.

== 1.2.5 - 2017-08-10

=== Improvements

  * Supported Homebrew bundled .pc files.
    [GitHub:rcairo/rcairo#49][Reported by choboy11]

=== Thanks

  * choboy11

== 1.2.4 - 2017-08-07

=== Improvements

  * Added `pkg-config` 0.29 or later compatible result support.
    [GitHub#13][Reported by HIGUCHI Daisuke]

  * test: Updated expected value for the latest cairo.
    [GitHub#14][Patch by HIGUCHI Daisuke]

=== Thanks

  * HIGUCHI Daisuke