Strange gitlab idea

[Simon Glass]

Hi Tom,

I notice that the runners are not utilised much by the QEMU jobs,
since we only run one at a time.

I wonder if we could improve this, perhaps by using a different tag
for the QEMU ones and then having a machine that only runs those (and
runs 40 in parallel)?

In general our use of the runners seems a bit primitive, since the
main use of parallelism is in the world builds.

Regards,
Simon