patch 8.1.0857: indent functionality is not separated

Problem:    Ignore functionality is not separated.
Solution:   Move indent functionality into a new file. (Yegappan Lakshmanan,
            closes #3886)
diff --git a/src/version.c b/src/version.c
index c0a239c..f7dd664 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    857,
+/**/
     856,
 /**/
     855,