don't build gio2-no-gi

Or it should be removed.
vte3: add missing prefix into comment

/* __RBGIO2CONVERSIONS_H__ */ ->
/* __VTE3_RBGIO2CONVERSIONS_H__ */
     ^^^^^
gio2: fix a typo

vlaidate ->
validate
 ^^
gi: fix free function for an array of UTF-8-STRING

Because RVAL2STRV doesn't copy elements in an array. So we should free
only container. We should not free internal elements.
gtk2: message_type is a property.
gtk2: remove trailing spaces
gtk2 test: add Gtk::InfoBar messageType accessors test
gtk3 sample: don't use deprecated widgets

  * VBox -> Box
  * ComboBox -> ComboBoxText
gtk3 sample: remove trailing spaces
gtk3 sample: use " (double quote) for string literal
gtk2: set_cursor is a property.

see: https://developer.gnome.org/gdk2/stable/gdk2-Windows.html
gtk2: remove trailing spaces
gtk2 test: add cursor accessor tests.
gtk2: In Gtk::Widget, window is `Read` property since gtk+2 2.14.0.

see: https://developer.gnome.org/gtk2/2.24/GtkWidget.html#GtkWidget--window
gtk2: remove trailing spaces