Cross compilation for aarch64 report

[shrx]

Hi, just wanted to let you know that it's possible to cross compile for aarch64 without too much effort (I managed to do it while totally unfamiliar with rust).

What I needed to do (information gathered by googling for similar problems):

1. Create a Cross.toml file with the following contents (not sure if all absolutely necessary):

[build]
default-target = "aarch64-unknown-linux-gnu"
pre-build = [
    "dpkg --add-architecture $CROSS_DEB_ARCH",
    "apt-get update",
    "apt-get install -y alsa-tools libasound2-dev libdbus-1-dev pkg-config",
    "apt-get install -y alsa-tools:$CROSS_DEB_ARCH libasound2-dev:$CROSS_DEB_ARCH libdbus-1-dev:$CROSS_DEB_ARCH",
    "cp -r /usr/lib/aarch64-linux-gnu/* /usr/aarch64-linux-gnu/lib/",
]

2. build with:

cross build --target=aarch64-unknown-linux-gnu --release

I first wanted to build it on my raspberry pi directly but I ran out of RAM.