patch 9.0.0804: crash when trying to divide a number by -1

Problem:    Crash when trying to divice the largest negative number by -1.
Solution:   Handle this case specifically.

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    804,
 /**/
     803,
 /**/