patch 8.0.1700: coverage statistics still don't work on coveralls

Problem:    Coverate statistics still don't work on coveralls.
Solution:   Exclude the xxd directory again.
diff --git a/src/version.c b/src/version.c
index 5f352cf..5386fc5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1700,
+/**/
     1699,
 /**/
     1698,