glib2: (maybe) fix a bug that wrong converter is used on bigendian environment
glib2: (maybe) fix a bug that wrong converter is used on bigendian environment

GitHub: #270

Reported by mtasaka. Thanks!!!

kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2,kitachro/ruby-gnome2