patch 8.1.0084: user name completion does not work on MS-Windows

Problem:    User name completion does not work on MS-Windows.
Solution:   Use NetUserEnum() to get user names. (Yasuhiro Matsumoto)
diff --git a/src/version.c b/src/version.c
index 20cd380..9d4d449 100644
--- a/src/version.c
+++ b/src/version.c
@@ -762,6 +762,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    84,
+/**/
     83,
 /**/
     82,