GtkButton: Don't use a non-zero border by default
GtkButton: Don't use a non-zero border by default

The non-zero default default-border was causing buttons to shrink as
the focus moves around them. Themes which want a default-border should
define it explicitly.

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