Log Message:
Update gtk3 to 3.20.9

Overview of Changes in GTK+ 3.20.9
==================================

* Bug fixes:
 769287 GtkMenuToolButton:show-menu is emitted twice and breaks dynamic m...
 769603 gtk+-3.20.8: underlink issue with ld.gold - build fails: ./.libs/...
        Fix headerbar size allocation
        Use g_snprintf instead of snprintf

* Translation updates
 Brazilian Portuguese
 Czech
 German
 Hungarian
 Indonesian
 Lithuanian
 Polish
 Portuguese
 Swedish