Prior to this patch, when testing target aarch64 CI builds on an amd64 host,
QEMU fails to attach a /dev/vtb1 tar device and the freebsdci rc script
fails to use it as a backing directory for kyua test reports. This fails the
entire run.
This patch uses the QEMU manpage-recommended '-blockdev' option instead of
'-drive' to declare block devices. This also makes the mandatory '-device'
declarations constant across all platforms, which fixes the missing QEMU_DEVICES tarfs device declarations on all `Makefile.<arch>` files.
Signed-off-by: Siva Mahadevan <me@svmhdvn.name>
Sponsored by: The FreeBSD Foundation