Log Message:
Update ruby-pkg-config to 1.1.3.

== 1.1.3 - 2012/01/29

  * [GitHub #8] fix test broken by libpng version.
    (Patch by Bohuslav Kabrda.)
  * Used RbConfig instead of Config.

== 1.1.2 - 2011/07/04

  * [GitHub #2] fix test broken.
    (Reported by Mamoru Tasaka.)
  * [GitHub #4] update project descripton.
    (Patch by Antonio Terceiro.)
  * [GitHub #4] use setup.rb instead of extconf.rb.
    (Patch by Antonio Terceiro.)
  * [GitHub #3] add Copyright notice to README.
    (Suggested by Antonio Terceiro.)
  * [GitHub #7] supported non i386 and amd64 architectures.
    (Reported by Antonio Terceiro.)