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
    "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