{
{ This procedure is used to generate FDE pointers to all FDE entries that are in use.
{ Note that the entry is NOT interlocked by this request.
{     Example:    gfp$scan_all_fdes (gfc$tr_system, state, fde_p)
{                 WHILE fde_p <> NIL DO
{                   xxx;
{                   gfp$scan_all_fdes (gfc$tr_null_residence, state, fde_p)
{                 WHILEND;
{
{
{    GFP$SCAN_ALL_FDES (RESIDENCE, STATE, FDE_P)
{
{
{ RESIDENCE: (INPUT)  On the FIRST call to this proc, this parameter indicates whether to
{      scan global or job FDEs. Subsequent calls (in the loop) should specify
{      gfc$tr_null_residence.
{
{ STATE: (INPUT/OUTPUT) Private state variable for the procedure.
{
{ FDE_P: (OUTPUT) Pointer to next FDE. NIL indicates end of scan.
