The FreeBSD jobs currently hit the 1h time limit in the Cirrus-CI.
We have to split the build targets here to make sure that the job
finishes in time again. According to the Cirrus-CI docs and some
tests that I did, it also seems like the total amount of CPUs that
can be used for FreeBSD jobs is limited to 8, so each job now only
gets 4 CPUs. That increases the compilation time of each job a little
bit, but it still seems to be better to run two jobs with 4 CPUs each
in parallel than to run two jobs with 8 CPUs sequentially.

Message-Id: <20200831154405.229706-1-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>