patch 8.1.0853: options test fails on Mac

Problem:    Options test fails on Mac.
Solution:   Remove a trailing slash from $TMPDIR.
diff --git a/src/version.c b/src/version.c
index 3652f43..97ef0c1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -784,6 +784,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    853,
+/**/
     852,
 /**/
     851,