patch 8.0.1696: coverage statistics don't work

Problem:    Coverate statistics don't work.
Solution:   Include the xxd directory. (Christian Brabandt)
diff --git a/src/version.c b/src/version.c
index 2b41fae..51e8259 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1696,
+/**/
     1695,
 /**/
     1694,