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/curses/cursmain.c

@@ -36,7 +36,7 @@ static char *dummy_get_color_string(void);
 
 /* Interface definition, for windows.c */
 struct window_procs curses_procs = {
-    "curses",
+    WPID(curses),
     (WC_ALIGN_MESSAGE | WC_ALIGN_STATUS | WC_COLOR | WC_INVERSE
      | WC_HILITE_PET
 #ifdef NCURSES_MOUSE_VERSION /* (this macro name works for PDCURSES too) */