patch 8.2.1703: ":highlight clear" does not restore default link

Problem:    ":highlight clear" does not restore default link.
Solution:   Remember the default link and restore it. (Antony Scriven,
            closes #6970, closes #4405)
diff --git a/src/version.c b/src/version.c
index 9d87cdb..f7e1720 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1703,
+/**/
     1702,
 /**/
     1701,