patch 8.1.1772: options test still fails on MS-Windows

Problem:    Options test still fails on MS-Windows.
Solution:   Check buffer-local value of 'completeslash'.
diff --git a/src/version.c b/src/version.c
index 5507f6a..29921e2 100644
--- a/src/version.c
+++ b/src/version.c
@@ -778,6 +778,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1772,
+/**/
     1771,
 /**/
     1770,