Fix for CONC-345: heap-use-after-free in client_mpvio_read_packet
Fix for CONC-345: heap-use-after-free in client_mpvio_read_packet

Kudos to Kentoku Shiba

ottok/mariadb-connector-c,MariaDB/mariadb-connector-c,ottok/mariadb-connector-c,ottok/mariadb-connector-c,MariaDB/mariadb-connector-c,MariaDB/mariadb-connector-c