patch 9.0.1157: "implements" only handles one interface name

Problem:    "implements" only handles one interface name.
Solution:   Handle a comma separated list of names.  Check for duplicate
            names.

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1157,
 /**/
     1156,
 /**/