clear errline and errfile after grn_dl_close() is succeeded.
clear errline and errfile after grn_dl_close() is succeeded.

Reported by @tomotaka_ito. Thanks!!!

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