patch 8.2.0965: has_funcundefined() is not used

Problem:    Has_funcundefined() is not used.
Solution:   Delete the function. (Dominique Pellé, closes #6242)
diff --git a/src/version.c b/src/version.c
index 25a0962..bc4cc43 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    965,
+/**/
     964,
 /**/
     963,