fixed coredump in concat_ws
sql/item_strfunc.h
    fixed coredump in concat_ws
sql/mini_client.cc
    added mc_mysql_error()
sql/mini_client.h
    added mc_mysql_errno()
sql/mysqlbinlog.cc
    fixed bug in --postion for local files
sql/slave.cc
    more verbose message on bad net reads
sql/sql_repl.cc
    send errno on error in mysql_binlog_send