patch 8.2.1259: empty group in 'tabline' may cause using an invalid pointer

Problem:    Empty group in 'tabline' may cause using an invalid pointer.
Solution:   Set the group start position. (closes #6505)
diff --git a/src/version.c b/src/version.c
index 1aacd3b..528c8c0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1259,
+/**/
     1258,
 /**/
     1257,