int mysql_kill(MYSQL *mysql, unsigned long pid)
20.4.30.1  Description
Asks the server to kill the thread specified by pid.
20.4.30.2  Return values
Zero for success.  Non-zero if an error occurred.
20.4.30.3  Errors
CR_COMMANDS_OUT_OF_SYNC
- 
Commands were executed in an improper order.
 CR_SERVER_GONE_ERROR
- 
The MySQL server has gone away.
 CR_SERVER_LOST
- 
The connection to the server was lost during the query.
 CR_UNKNOWN_ERROR
- 
An unknown error occurred.