Update to 3.5.8

Overview of Changes in GTK+ 3.5.8
=================================

* gtk-launch: A new commandline utility to launch an application
  from its desktop file

* GtkStrengthBar: A new widget for displaying the strength
  or level or some quantity

* Wayland: Updates for changes in the Wayland protocol

* Bugs fixed:
 667808 Accept -1 as the position where insert an element...
 671437 GtkStyle background color regression
 671817 GTK+ doesn't create ~/.local/share (path) and ~/.local...
 675990 gtk_tree_column_set_visible badly interact with the a1...
 677347 he accessible name of the 'Lock'/'Unlock' button is al...
 677491 'toolkit-accessibility' default value should be 'true'...
 678828 gtk_application_add_accelerator() (and remove) missing...
 678829 Bloatpad example application has "parse" action instea...
 679092 gtkstyle: add a gtkstyle-fallback style class for RC c...
 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
 679449 menubutton: set DROPDOWN_MENU hint on the menu topleve...
 679454 modelmenu: listen for toplevel changes on the attach w...
 679537 Crash in GtkEntry gtk_entry_get_icon_pixbuf()
 679705 Using NULL with gtk_application_set_menubar causes seg...
 677892 Add a GtkStrengthBar widget
 679342 Add a gtk-launch utility

* Translation updates:
 Bulgarian
 Greek
 Norwegian nynorsk
 Telugu
 Vietnamese