#4700 (Unsigned value returned as signed)
    just no appropriate checking
#4701 (Errors returned earlier than expected)
    all errors returned from send_command()
#4702 (Result isn't freed properly if there's no retrieval)
    flush_use_result has only 'client' version and should
    be made 'virtual'


include/mysql.h:
  flush_use_result 'virtual' method added to MYSQL (#4701)
include/sql_common.h:
  no flush_use_result() now (#4702)
libmysql/libmysql.c:
  call of the flush_use_result changed (#4702)
libmysqld/lib_sql.cc:
  now errors returned from emb_advanced_command() or from emb_read_rows()
  depending on if number of returned fields is not 0 (#4701)
  emb_flush_use_result() implementation (#4702)
sql-common/client.c:
  cli_flush_use_result() implementation (#4702)
sql/sql_prepare.cc:
  unsigned flag now checked (#4700)