Mariadb101-server ignores datadir in my.cfg

[scratch65535 at att.net]

MariaDB 10.1 server ignores the datadir directive in my.cfg,
creating new databases only in /var/db/mysql.

The port claims that it honors hier(7), but hier(7) specifies
that /var/db is to be used for "miscellaneous automatically
generated system-specific database files", which mariadb/mysql
database files certainly are not.

(This bug was first reported in October 2014, about v5.  No known
response from the maintainer since then)