CLIENT_DEPRECATE_EOF : Client must identify a "stored procedure output resultset"

MDEV-8931 implement a new capacity CLIENT_DEPRECATE_EOF that deprecate EOF packet.

Store procedure output parameter identification
When calling a store procedure with output parameters - using prepare statement - server send output parameter in a resultset if client has CLIENT_PS_MULTI_RESULTS capacity. Client must identify this resultset as an "output parameter resultset". This was actually done by a flag on the deleted EOF packet.

Example :

DELIMITER //

create procedure prepareStmtWithOutParameter (x int, INOUT y int) 

BEGIN

SELECT 1; 

end;

//

DELIMITER ;

prepare test from "call prepareStmtWithOutParameter(?,?)";

set @param1=1;

set @param2=2;

execute test using @param1, @param2;

For this example, if client has CLIENT_PS_MULTI_RESULTS capacity, server will send 2 differents resultset :

• first one corresponding to "SELECT 1; "
• second result-set contain the INOUT integer parameter "y"

Before CLIENT_DEPRECATE_EOF capability, client can identify that resultset is an "output parameter resulset" with the EOF packet server status value.
Flag SERVER_PS_OUT_PARAM indicate that resultset is an "output param" resultset.

A resultset has 2 EOF packet. SERVER_PS_OUT_PARAM flag is set only on first EOF.
If CLIENT_DEPRECATE_EOF is set, first EOF is deleted, second has to have the SERVER_PS_OUT_PARAM flag.