Cross compile librespot for Raspberry Pi 2 (ARMv7) using Debian

[roqueeee]

I used PR #1405 as a basis when trying to cross compile librespot on Debian but found that I had to jump through a few extra hoops in order to successfully cross compile librespot for the Raspberry Pi 2. So I wanted to share my findings with the community, maybe someone will find it helpful.

These are steps I took when building librespot with Avahi and the PulseAudio backend on Debian 12:

# install dependencies
sudo apt install build-essential pkg-config gcc-arm-linux-gnueabihf cmake clang

# install required armhf libraries
sudo dpkg --add-architecture "armhf"
sudo apt update
sudo apt install libssl-dev:armhf libpulse-dev:armhf

# install required rust target
rustup target add armv7-unknown-linux-gnueabihf

# build with armhf linker and PKG_CONFIG_SYSROOT_DIR pointing to armhf directory
RUSTFLAGS="-C linker=arm-linux-gnueabihf-gcc" PKG_CONFIG_SYSROOT_DIR="/usr/arm-linux-gnueabihf" cargo build --release --target armv7-unknown-linux-gnueabihf --no-default-features --features "native-tls pulseaudio-backend with-avahi"

Cross compiling librespot with a 4-core Debian VM running on an M2 Mac took around 1m 30s. A considerable improvement over the 1 or 2 hours this takes on a Raspberry Pi 2. I verified that the resulting binary works on Raspberry Pi 2.

Edit: Updated for v0.7.0