patch 8.1.1966: some code in options.c fits better elsewhere

Problem:    Some code in options.c fits better elsewhere.
Solution:   Move functions from options.c to other files. (Yegappan
            Lakshmanan, closes #4889)
diff --git a/src/version.c b/src/version.c
index af01f26..984a984 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1966,
+/**/
     1965,
 /**/
     1964,