Use JS_NewNumberValue() rather than INT_TO_JSVAL() for system.datestr()

conversion from string.  This allows dates from the last couple years to work

*cough*

src/sbbs3/js_system.c

@@ -938,8 +938,7 @@ js_datestr(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
 		t=time(NULL);	/* use current time */
 	else {
 		if(JSVAL_IS_STRING(argv[0])) {	/* convert from string to time_t? */
-			*rval = INT_TO_JSVAL(
-				dstrtounix(cfg,JS_GetStringBytes(JS_ValueToString(cx, argv[0]))));
+			JS_NewNumberValue(cx,dstrtounix(cfg,JS_GetStringBytes(JS_ValueToString(cx, argv[0]))),rval);
 			return(JS_TRUE);
 		}
 		JS_ValueToInt32(cx,argv[0],(int32*)&t);