gtk: don't leak the GtkBorder with VTE 0.36

gtk: don't leak the GtkBorder with VTE 0.36

When gtk_widget_style_get() is used to get the "inner-border" style
property, it returns a copy of the GtkBorder which must be freed by
the caller.

This patch also fixes a warning about the unused 'padding' structure
with VTE 0.36.

Signed-off-by: Alberto Garcia <[email protected]>
Message-id: 1463127654[email protected]
Cc: Cole Robinson <[email protected]>
Cc: Gerd Hoffmann <[email protected]>
[ kraxel: adapted to changes in ui patch queue ]

Signed-off-by: Gerd Hoffmann <[email protected]>