- Use "mysql_stmt_field_count" to determine if there is a need to
call "mysql_stmt_store_result"


client/mysqltest.c:
  Only call 'mysql_stmt_store_result' if 'mysql_stmt_field_count' is
  greater than 0 indicating that this query has a result set.
  This change is mainly since if mysql_stmt_store_result fails
  the value returned by mysql_stmt_field_count will be reset.