patch 8.2.1970: it is easy to make mistakes when cleaning up swap files

Problem:    It is easy to make mistakes when cleaning up swap files after the
            system crashed.
Solution:   Warn for the process still running after recovery.  Do not
            automatically delete a swap file created on another system.
            (David Fries, closes #7273)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1970,
 /**/
     1969,
 /**/