patch 8.0.1695: xxd test not run on MS-Windows

Problem:    Xxd test not run on MS-Windows.
Solution:   Use xxd.exe if it exists.
diff --git a/src/version.c b/src/version.c
index 46d12cc..2b41fae 100644
--- a/src/version.c
+++ b/src/version.c
@@ -763,6 +763,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1695,
+/**/
     1694,
 /**/
     1693,