Use locale independent function for sorting.
Use locale independent function for sorting.

Reported by Yoshinori K. Okuji. Thanks!!!

groonga/groonga,groonga/groonga,cosmo0920/groonga,cosmo0920/groonga,redfigure/groonga,cosmo0920/groonga,groonga/groonga,cosmo0920/groonga,myokoym/groonga,cosmo0920/groonga,myokoym/groonga,hiroyuki-sato/groonga,kenhys/groonga,naoa/groonga,hiroyuki-sato/groonga,redfigure/groonga,groonga/groonga,hiroyuki-sato/groonga,hiroyuki-sato/groonga,kenhys/groonga,komainu8/groonga,komainu8/groonga,redfigure/groonga,hiroyuki-sato/groonga,kenhys/groonga,redfigure/groonga,groonga/groonga,cosmo0920/groonga,groonga/groonga,kenhys/groonga,komainu8/groonga,myokoym/groonga,komainu8/groonga,myokoym/groonga,redfigure/groonga,naoa/groonga,hiroyuki-sato/groonga,myokoym/groonga,komainu8/groonga,groonga/groonga,redfigure/groonga,naoa/groonga,cosmo0920/groonga,naoa/groonga,kenhys/groonga,myokoym/groonga,groonga/groonga,cosmo0920/groonga,redfigure/groonga,kenhys/groonga,kenhys/groonga,redfigure/groonga,hiroyuki-sato/groonga,myokoym/groonga,komainu8/groonga,hiroyuki-sato/groonga,naoa/groonga,kenhys/groonga,komainu8/groonga,naoa/groonga,naoa/groonga,komainu8/groonga,naoa/groonga,myokoym/groonga