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.
diff --git a/src/version.c b/src/version.c
index f30cdfd..d2efc12 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1157,
+/**/
     1156,
 /**/
     1155,