job-list: cleanup correct memory on error path

Problem: In the idsync_add_waiter() function, the cleanup path cleaned
up the wrong memory.

Solution: Clean up the zlistx_t that was possibly created within the function,
not the data structure passed in as a parameter.

Author: chu11

src/modules/job-list/idsync.c

@@ -193,7 +193,7 @@ static int idsync_add_waiter (struct idsync_ctx *isctx,
     return 0;
 
 enomem:
-    idsync_data_destroy (isd);
+    zlistx_destroy (&list_isd);
     errno = ENOMEM;
     return -1;
 }