patch 8.1.0414: v:option_old is cleared when using :set in OptionSet autocmd

Problem:    v:option_old and v:option_new are cleared when using :set in
            OptionSet autocmd. (Gary Johnson)
Solution:   Don't trigger OptionSet recursively.
diff --git a/src/version.c b/src/version.c
index 0e20abf..3ce73b9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -795,6 +795,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    414,
+/**/
     413,
 /**/
     412,