patch 8.2.3252: duplicated code for adding buffer lines

Problem:    Duplicated code for adding buffer lines.
Solution:   Move code to a common function.  Also move map functions to map.c.
            (Yegappan Lakshmanan, closes #8665)
diff --git a/src/version.c b/src/version.c
index 046d1e7..ebd2c56 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3252,
+/**/
     3251,
 /**/
     3250,