gtk3+: update to 3.22.26.

Overview of Changes in GTK+ 3.22.26
===================================

* Bugs fixed:
789630 Distribute protocol/server-decoration.xml in tarballs
787142 input/IME: Defer the emit of the "commit" signal
789134 icon-browser: Centre Copy button in dialog again
789678 AboutDialog: Fix accepting GTK_LICENSE_AGPL_3_0
788898 Inspector: better default split of CSS nodes/props
789733 Fix GtkEntry:has-frame not working
789213 gdk/win32: Fix Win32 GL Context switching
785176 placessidebar: add starred location item

* Translation updates:
Arabic
Brazilian Portuguese
Czech
Dutch
German
Norwegian bokm奪l
Polish
Slovak
Swedish

(wiz)