patch 9.0.0081: command line completion of user command may have duplicates

Problem:    Command line completion of user command may have duplicates.
            (Dani Dickstein)
Solution:   Skip global user command if an identical buffer-local one is
            defined. (closes #10797)

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    81,
 /**/
     80,
 /**/