arch-run: DRYRUN is no longer needed, kill it

Signed-off-by: Andrew Jones <drjones@redhat.com>
Message-Id: <1453474709-10679-4-git-send-email-drjones@redhat.com>
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>