NAME
	AddHead -- insert node at the head of a list

   SYNOPSIS
	AddHead(list, node)
		A0    A1

	void AddHead(struct  List *, struct  Node *)

   FUNCTION
	Add a node to the head of a doubly linked list. Assembly
	programmers may prefer to use the ADDHEAD macro from
	"sc:include/exec/lists.i".

   WARNING
	This function does not arbitrate for access to the list.  The
	calling task must be the owner of the involved list.

   INPUTS
	list - a pointer to the target list header
	node - the node to insert at head

   SEE ALSO
	 AddTail,  Enqueue,  Insert,  Remove,  RemHead,  RemTail