patch 8.0.1693: xxd is excluded from coverage statistics

Problem:    Xxd is excluded from coverage statistics.
Solution:   Don't skip the xxd directory. (Christian Brabandt)
diff --git a/src/version.c b/src/version.c
index 6a8cd23..80b05fa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1693,
+/**/
     1692,
 /**/
     1691,