Initialize the scrollbar spacing variable in the class to -1, and then

Initialize the scrollbar spacing variable in the class to -1, and then

Fri Mar  1 16:48:19 2002  Owen Taylor  <otaylor@redhat.com>

	* gtk/gtkscrolledwindow.c: Initialize the scrollbar spacing
	variable in the class to -1, and then take that to mean
	"default" (3) rather than putting 3 in the class directly.
	This gives us some wiggle room to make it a per-instance
	rather than a per-class property later.