patch 8.0.1720: when a timer is running a terminal window may not close

Problem:    When a timer is running a terminal window may not close after a
            shell has exited.
Solution:   Call job_status() more often.

src/version.c

@@ -762,6 +762,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1720,
 /**/
     1719,
 /**/