patch 9.0.0531: the win_line() function is much too long

Problem:    The win_line() function is much too long.
Solution:   Move code to separate functions.
diff --git a/src/version.c b/src/version.c
index cefa82a..29a1b92 100644
--- a/src/version.c
+++ b/src/version.c
@@ -700,6 +700,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    531,
+/**/
     530,
 /**/
     529,