qemu-system-aarch64 2.12.1

``` shell
https://download.qemu.org/qemu-2.12.1.tar.xz
tar xf qemu-2.12.1.tar.xz
cd qemu-2.12.1
./configure --target-list=aarch64-softmmu --disable-gtk --disable-vnc --disable-vhost-net --disable-vhost-vsock --disable-vhost-user --disable-vhost-scsi --disable-vhost-crypto --disable-libxml2 --disable-libusb --disable-tpm --disable-kvm --disable-qom-cast-debug --disable-guest-agent --disable-replication --disable-live-block-migration --disable-blobs
make
strip aarch64-softmmu/qemu-system-aarch64
```