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.
diff --git a/src/version.c b/src/version.c
index 7ce1c9c..2d28206 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1720,
+/**/
     1719,
 /**/
     1718,