Reminder to self:

    echo "https://ftp.eu.openbsd.org/pub/OpenBSD/" >/etc/installurl
    pkg_add git autoconf automake

Select the latest versions, then add the following to ~/.profile:

    AUTOCONF_VERSION=2.69
    AUTOMAKE_VERSION=1.15
    export AUTOCONF_VERSION AUTOMAKE_VERSION

With your selected versions, of course.