patch 8.1.0572: stopping a job does not work properly on OpenBSD

Problem:    Stopping a job does not work properly on OpenBSD.
Solution:   Do not use getpgid() to check the process group of the job
            processs ID, always pass the negative process ID to kill().
            (George Koehler, closes #3656)

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    572,
 /**/
     571,
 /**/