qemu: capabilities: Replace aliased machine type by copy of the canonical machine

The previous approac of just purging the alias combined with the fact
that we filled in fake machine types in the test data meant that if a
test case used an alias machine type such as 'pc' or 'q35' it would not
properly resolve to the actual data returned by qemu.

This started to be a problem since the CPU driver now looks at the
default CPU reported with the machine type.

This patch replaces the original approach of just removing the alias by
replacing it with a copy of the machine type data which the type would
alias to. This means that we are using the real data while we don't
modify the test output after every qemu upgrade.

Additionally this change will allow us to drop adding the fake machine
types later.

The test fallout is from actually excercising the CPU driver with
actual data.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

tests/qemuxml2argvdata/hostdev-subsys-mdev-vfio-ccw-boot.s390x-latest.args

@@ -13,6 +13,7 @@ QEMU_AUDIO_DRV=none \
 -object secret,id=masterKey0,format=raw,\
 file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
 -machine s390-ccw-virtio,accel=tcg,usb=off,dump-guest-core=off \
+-cpu qemu \
 -m 512 \
 -overcommit mem-lock=off \
 -smp 2,sockets=2,cores=1,threads=1 \