patch 8.0.1595: no autocommand triggered before exiting

Problem:    No autocommand triggered before exiting.
Solution:   Add the ExitPre autocommand event.

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1595,
 /**/
     1594,
 /**/