patch 8.0.0581: moving folded text is sometimes not correct

Problem:    Moving folded text is sometimes not correct.
Solution:   Bail out when "move_end" is zero. (Matthew Malcomson)
diff --git a/src/version.c b/src/version.c
index c41cc5a..3f74d6e 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    581,
+/**/
     580,
 /**/
     579,