patch 7.4.901

Problem:    When a BufLeave autocommand changes folding in a way it syncs
            undo, undo can be corrupted.
Solution:   Prevent undo sync. (Jacob Niehus)

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    901,
 /**/
     900,
 /**/