patch 8.1.0516: :move command marks buffer modified when nothing changed

Problem:    :move command marks buffer modified when nothing changed.
Solution:   Do not set 'modified'.  Add a test. (Jason Franklin)
diff --git a/src/version.c b/src/version.c
index 3d72854..12b8688 100644
--- a/src/version.c
+++ b/src/version.c
@@ -793,6 +793,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    516,
+/**/
     515,
 /**/
     514,