annotations: Set GtkTreeModelFilterModifyFunc value argument to out
annotations: Set GtkTreeModelFilterModifyFunc value argument to out

Use (out caller-allocates) annotation for the "value" argument to
GtkTreeModelFilterModifyFunc. This is needed because GI based language
bindings coerce GValue input args into native types and there is no
opportunity to set the value within the GValue itself.

https://bugzilla.gnome.org/show_bug.cgi?id=719460

ahodesuka/gtk,davidgumberg/gtk,Lyude/gtk-,Adamovskiy/gtk,jigpu/gtk,jessevdk/gtk,ahodesuka/gtk,Lyude/gtk-,alexlarsson/gtk,msteinert/gtk,Lyude/gtk-,alexlarsson/gtk,Adamovskiy/gtk,jadahl/gtk,alexlarsson/gtk,grubersjoe/adwaita,Adamovskiy/gtk,Adamovskiy/gtk,chergert/gtk,jadahl/gtk,jadahl/gtk,grubersjoe/adwaita,msteinert/gtk,grubersjoe/adwaita,alexlarsson/gtk,jadahl/gtk,jessevdk/gtk,grubersjoe/adwaita,jadahl/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,Sidnioulz/SandboxGtk,msteinert/gtk,Lyude/gtk-,davidgumberg/gtk,jessevdk/gtk,jigpu/gtk,alexlarsson/gtk,grubersjoe/adwaita,Lyude/gtk-,chergert/gtk,Adamovskiy/gtk,Adamovskiy/gtk,jessevdk/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,davidgumberg/gtk,alexlarsson/gtk,Adamovskiy/gtk,Sidnioulz/SandboxGtk,Sidnioulz/SandboxGtk,jadahl/gtk,msteinert/gtk,grubersjoe/adwaita,chergert/gtk,chergert/gtk,jessevdk/gtk,jigpu/gtk,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,Adamovskiy/gtk,ahodesuka/gtk,jessevdk/gtk,davidgumberg/gtk,jadahl/gtk,jigpu/gtk,ahodesuka/gtk,chergert/gtk,grubersjoe/adwaita,Lyude/gtk-,ahodesuka/gtk,jigpu/gtk,davidgumberg/gtk,jigpu/gtk,grubersjoe/adwaita,ahodesuka/gtk,davidgumberg/gtk,alexlarsson/gtk,ahodesuka/gtk,chergert/gtk,Sidnioulz/SandboxGtk,Lyude/gtk-,msteinert/gtk,chergert/gtk,jessevdk/gtk,msteinert/gtk,jadahl/gtk,alexlarsson/gtk,Lyude/gtk-,chergert/gtk