Curses: prevent spurious cursor updates

While watching a ttyrec, I noticed strange behaviour in
the cursor updates; it was moved to approximately middle
of the map window every so often, usually when doing ranged
attacks. This wasn't really noticeable in normal gameplay,
as it was moving the cursor there, and then almost immediately
to where it was supposed to be.

I managed to trace it down to the refresh() in curses_delay_output().
That call updates the terminal to match the ncurses stdscr window,
but the stdscr window cursor position wasn't updated by NetHack.

win/curses/cursmisc.h

@@ -22,6 +22,7 @@ boolean curses_is_menu(winid wid);
 boolean curses_is_text(winid wid);
 int curses_convert_glyph(int ch, int glyph);
 void curses_move_cursor(winid wid, int x, int y);
+void curses_update_stdscr_cursor(void);
 void curses_prehousekeeping(void);
 void curses_posthousekeeping(void);
 void curses_view_file(const char *filename, boolean must_exist);