patch 8.2.5131: timeout implementation is not optimal

Problem:    Timeout implementation is not optimal.
Solution:   Further improvements for timeouts.  Add a test for searchpair()
            timeout. (partly by Paul Ollis)

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    5131,
 /**/
     5130,
 /**/