patch 8.1.0873: list if distributed files does not include matchit autoload

Problem:    List if distributed files does not include the matchit autoload
            directory.
Solution:   Add the directory.

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    873,
 /**/
     872,
 /**/