patch 8.1.2129: using hard coded executable path in test

Problem:    Using hard coded executable path in test.
Solution:   Use v:progpath. Use $VIMRUNTIME instead of "runtime". (James
            McCoy, closes #5025)
diff --git a/src/version.c b/src/version.c
index 7ad0acd..f9a3028 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2129,
+/**/
     2128,
 /**/
     2127,