Update after F28 EOL
    Remove Cassandra SE; it is no longer developed: https://mariadb.com/kb/en/library/cassandra-storage-engine-overview
    Fix typos
    Remove unnecessary -fPIC; it is already applied by cmake SECURITY_HARDENED option
    Update dead hypertext links
    Stop providing "mariadb-galera"
    Remove comments after %endif to comply with RPM syntax