Merge from vendor branch BIND:

Merge from vendor branch BIND:
Add BIND 9.2.4rc7.

Notable changes:

1643.   [bug]           dns_db_closeversion() could leak memory / node
                        references. [RT #11163]

1650.   [bug]           dig, nslookup: flush standard out after each command.

1654.   [bug]           isc_result_totext() contained array bounds read
                        error.

1681.   [bug]           Only set SO_REUSEADDR when a port is specified in
                        isc_socket_bind(). [RT #11742]

1686.   [bug]           Named sent a extraneous NOTIFY when it received a
                        redundant UPDATE request. [RT #11943]

1687.   [bug]           Race condition in dispatch. [RT #10272]

1690.   [bug]           Delay detaching view from the client until UPDATE
                        processing completes when shutting down. [RT #11714]