Minor update, but with lots of bugfixes - we should look into if we want to push this for 12.2.

* Bugs fixed:
531319 "weight-set" cellrenderertext attribute misbehaves...
571254 Constructing a pixel value from components
613561 single quote missing in translation of gtk-2-18.kn.po
643490 gtk-style-context-add-provider () documentation ne...
646798 Add a tip about "cloning contexts"
647779 Doesn't mention GtkDialog replacements
649569 GDK_THREADS_ENTER in file_print_cb@modules/printba...
659613 GtkLockButton docs are inaccurate
663991 _XOPEN_SOURCE 500 causes error in Solaris Studio c...
664646 dnd pointer lock when dragging tab between two ged...
667808 Accept -1 as the position where insert an element ...
670369 gdk: annotate the attributes_mask type for gdk_win...
671437 GtkStyle background color regression
671817 GTK+ doesn't create ~/.local/share (path) and ~/.l...
673749 Error Message When Creating Tray Icon
675167 GtkPlug gets key translation wrong with multiple l...
675423 doc: Add missing CDATA around a XML programlisting...
675535 GtkScale in GtkToolbar: strange behaviour with dou...
675809 Crash when clicking xrefs
675899 Infobar not loadable by GTKBuilder (using python g...
675990 gtk_tree_column_set_visible badly interact with th...
676077 Windows: Weird characters appearing when using cer...
676243 Document removing of accelerators
676262 Build failure in gdk
676329 GDK_SMOOTH_SCROLL_MASK lacks "Since"
677127 Misc annotation fixes
677293 GtkFontSelectionDialog partially broken on gtk 3.4
677363 grid: Add missing guard to gtk_grid_get_child_at()
677551 a11y: fix a typo leading to a crash
677649 gtk[list,tree]store: fix transformation of GValues...
677774 gdk: add missing annotations to gdk_event_get_scro...
677775 gdk: add a missing annotation to GdkEventProperty
677809 Regression: gtkiconview changes in 3.4.2 / master ...
677915 entry-completion: don't move to leftmost character...
677941 Gtk.ListStore doesn't have the method "reorder" as...
678175 [Patch] Memory leak in GtkImage
678407 GtkImage: fix get_property('stock')
678829 Bloatpad example application has "parse" action in...
679166 modelmenu: set the accel group on the GtkMenu
679228 signal parameter names are not valid C identifiers
679409 docs: link against libgdk-3.la
679454 modelmenu: listen for toplevel changes on the atta...
679537 Crash in GtkEntry gtk_entry_get_icon_pixbuf() (forwarded request 127953 from dimstar)