patch 8.1.0120: buffer 'modified' set even when :sort has no changes

Problem:    Buffer 'modified' set even when :sort has no changes.
Solution:   Only set 'modified' when lines are moved. (Jason Franklin)
diff --git a/src/version.c b/src/version.c
index a7a96b3..aa8a1de 100644
--- a/src/version.c
+++ b/src/version.c
@@ -790,6 +790,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    120,
+/**/
     119,
 /**/
     118,