MDEV-4575 MySQL client doesn't strip off 5.5.5- prefix while connecting to 10.x server
MDEV-4575 MySQL client doesn't strip off 5.5.5- prefix while connecting to 10.x server

extend 5.1 client library to read 4 byte capabilities from the first handshake packet.
two higher bytes are always zeros for 5.1 servers.

davidl-zend/zenddbi,natsys/mariadb_10.2,davidl-zend/zenddbi,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix,ollie314/server,ollie314/server,slanterns/server,ollie314/server,ollie314/server,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,flynn1973/mariadb-aix,natsys/mariadb_10.2,davidl-zend/zenddbi,ollie314/server,davidl-zend/zenddbi,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,ollie314/server,ollie314/server,natsys/mariadb_10.2,natsys/mariadb_10.2,davidl-zend/zenddbi,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,flynn1973/mariadb-aix,ollie314/server,flynn1973/mariadb-aix,davidl-zend/zenddbi,flynn1973/mariadb-aix