server".

Altough mysql_create_db()/mysql_drop_db() API calls are deprecated
since 4.0, they should not crash server and should not stall connection
in case of errors. 


sql/sql_parse.cc:
  Handling of COM_CREATE_DB, COM_DROP_DB:
    mysql_create_db() requires from its second parameter to be non-zero.
    We also should call send_error() if mysql_create_db or mysql_drop_db
    return error (like we do it for SQL versions of these commands).
tests/client_test.c:
  Added test for bug #6081 "Execution of deprecated mysql_create_db()
  crashes server".