gtk+ 3.22.7 release.

Bugs fixed:

• 165385 Win32 keyboard handling still incomplete
• 769214 keyval field not filled correctly for Pause key
• 769835 On Wayland, application containing GtkGLArea stops responding if it's not...
• 774726 GtkTreeView dnd: gtk_drag_finish remove row when reorder sinse 3.20
• 775846 gdk/wayland: Add support for the gtk-enable-primary-paste gsetting
• 776031 W32: Winkey+down minimizes maximized window instead of restoring it
• 776225 [wayland] dropdown placed somewhere in the screen
• 776485 GDK W32: Impossible to restore maximized window via system menu
• 776807 GtkInspector doesn't show up when Gtk is initialized through option group
• 777031 win32 HiDPI assert
• 777176 [wayland] gedit killed by protocol error "Invalid anchor rectangle size"