Check that "$QEMU -M none -cpu FOO" starts QEMU without error

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1518000027-274608-3-git-send-email-imammedo@redhat.com>
[ehabkost: include qmp/qdict.h instead of qmp/types.h]
[ehabkost: add riscv targets to machine-none-test]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>