patch 8.2.0874: signals test is a bit flaky

Problem:    Signals test is a bit flaky.
Solution:   Flush the XautoOut file.  Delete files that may be left behind
            from a failure. (Dominique Pelle, closes #6179)

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    874,
 /**/
     873,
 /**/