Include vars.h in wserv.c and scr-bx.c for enum VAR_TYPES

Also define STERM_C and include modval.h in scr-bx.c.

This allows us to remove the slightly bogus dummy definition of enum VAR_TYPES from modval.h, and use a simple
macro to redirect the declaration and use of get_int_var() to BX_get_int_var().

source/wserv.c

@@ -22,6 +22,7 @@ static	char	rcsid[] = "@(#)$Id$";
 
 #include "ircterm.h"
 #include "ircaux.h"
+#include "vars.h"
 #define WTERM_C
 #include "modval.h"
 #include <errno.h>