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: implement Gtk::SearchBar