Added a test for pre-statement call, and fixed connection/deconnect code so that the rest of bbench can be ran by others. 


client/client_priv.h:
  Clean up of options.
client/mysqlslap.c:
  Cleanup of the connection and reconnect code.
mysql-test/r/mysqlslap.result:
  Add of new test.
mysql-test/t/mysqlslap.test:
  Additional test.