dropbear server: support -T max auth tries Add support for '-T n' for a run-time specification for maximum number of authentication attempts where 'n' is between 1 and compile time option MAX_AUTH_TRIES. A default number of tries can be specified at compile time using 'DEFAULT_AUTH_TRIES' which itself defaults to MAX_AUTH_TRIES for backwards compatibility. Signed-off-by: Kevin Darbyshire-Bryant <[email protected]>