updated for version 7.3.820

Problem:    Build errors and warnings when building with small features and
            Lua, Perl or Ruby.
Solution:   Add #ifdefs and UNUSED.

src/version.c

@@ -725,6 +725,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    820,
 /**/
     819,
 /**/