updated window_procs

Add a non-string identifier to window_procs for use in runtime
identification of the current window port being used.

Use a macro WPID to add the identification at the top of the
various existing window_procs declarations. It expands to the
existing text string, as well as the newly added field wp_id
with a wp_ identifier.

For example, WPID(tty) expands to: "tty", wp_tty

The generated wp_tty must be present in the wp_ids enum at
the top of include/winprocs.h.

The WINDOWPORT(x) macro has been updated to expand to a simple
value comparison (port.wp_id == wp_x), instead of a
string comparison.

win/X11/winX.c

@@ -100,7 +100,7 @@ static XtSignalId X11_sig_id;
 
 /* Interface definition, for windows.c */
 struct window_procs X11_procs = {
-    "X11",
+    WPID(X11),
     ( WC_COLOR | WC_INVERSE | WC_HILITE_PET | WC_ASCII_MAP | WC_TILED_MAP
      | WC_PLAYER_SELECTION | WC_PERM_INVENT | WC_MOUSE_SUPPORT ),
     /* status requires VIA_WINDOWPORT(); WC2_FLUSH_STATUS ensures that */