updated for version 7.3.516
Problem:    extend(o, o) may crash Vim.
Solution:   Fix crash and add test. (Thinca and Hirohito Higashi)
diff --git a/src/version.c b/src/version.c
index 317a2d1..5b4bbfc 100644
--- a/src/version.c
+++ b/src/version.c
@@ -715,6 +715,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    516,
+/**/
     515,
 /**/
     514,