curses: include date.h

This way the curses port will show the version and compile date
on the startup banner, just like tty does.

win/curses/cursinit.c

@@ -8,6 +8,7 @@
 #include "wincurs.h"
 #include "cursinit.h"
 #include "patchlevel.h"
+#include "date.h"
 
 #include <ctype.h>