Debian adds LoongArch support

The Debian project has addedthe LoongArch architecture to its ports collection.

After an initial manual bootstrap of roughly 200 packages, twobuildds are now building packages for the newly added "loong64"port with the help of qemu-user. After enough packages have beenbuilt for the port to be self-hosting, we're planning to replacethese two buildds with real hardware hosted at Loongson.