Use single define for max message history

... instead of having every windowport define their own variant.
Affects tty, curses, X11, and Windows GUI.

include/wincurs.h

@@ -33,7 +33,6 @@ extern WINDOW *activemenu;         /* curses window for menu requesting a
 #define MAP_WIN     3
 #define INV_WIN     4
 #define NHWIN_MAX   5
-#define MESG_HISTORY_MAX   200
 #if !defined(__APPLE__) || !defined(NCURSES_VERSION)
 # define USE_DARKGRAY /* Allow "bright" black; delete if not visible */
 #endif  /* !__APPLE__ && !PDCURSES */