OPENAFS-SA-2018-002 kaserver: prevent KAM_ListEntry information leak

KAM_ListEntry (kas list) does not initialize its output correctly.  It
leaks kaserver memory contents over the wire:

struct kaindex
- up to 64 bytes for member name
- up to 64 bytes for member instance

Initialize the buffer.

[kaduk@mit.edu: move initialization to top of server routine]

Change-Id: I5cc430fc996e7e89d38a384d092b9d4fad248fa4

src/kauth/kaprocs.c

@@ -1700,6 +1700,7 @@ kamListEntry(struct rx_call *call,
     afs_int32 caller;
     struct kaentry tentry;
 
+    memset(name, 0, sizeof(*name));
     COUNT_REQ(ListEntry);
     if ((code = InitAuthServ(&tt, LOCKREAD, this_op)))
 	return code;