patch 9.0.0530: using freed memory when autocmd changes mark

Problem:    Using freed memory when autocmd changes mark.
Solution:   Copy the mark before editing another buffer.
diff --git a/src/version.c b/src/version.c
index 555adf5..cefa82a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    530,
+/**/
     529,
 /**/
     528,