If we want to continue to split build and check phase it seems like a
good idea to allow building of the tests during our multi-threaded
build phase.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200701135652.1366-40-alex.bennee@linaro.org>