gdk_pixbuf2 windows: upgrade bundled gdk-pixbuf
gdk_pixbuf2 windows: upgrade bundled gdk-pixbuf

  * 2.30.2 ->
  * 2.30.6

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