feat: use rustembedded/cross images and use static relocation model to fix cross-compile

cross/build.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+set -ex
+
+# build custom container with libclang and static compilation
+tag="rust-cross:${TARGET:?}"
+docker build --tag="$tag" - << EOF
+FROM rustembedded/cross:$TARGET
+
+# Install libclang for generating bindings with rust-bindgen
+# The architecture is not relevant here since it's not used for compilation
+RUN apt-get update && \
+    apt-get install --assume-yes libclang-dev
+
+# Set the target prefix
+ENV TARGET_PREFIX="/usr/local/$(echo "${TARGET:?}" | sed -e 's/armv7/arm/' -e 's/-unknown//')"
+
+# Make sure that cc-rs links libc/libstdc++ statically when cross-compiling
+# See https://github.com/alexcrichton/cc-rs#external-configuration-via-environment-variables for more information
+ENV RUSTFLAGS="-L\$TARGET_PREFIX/lib" CXXSTDLIB="static=stdc++"
+# Forcefully linking against libatomic, libc and libgcc is required for arm32, otherwise symbols are missing
+$([[ $TARGET =~ arm ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -Clink-arg=-lgcc -Clink-arg=-latomic -lstatic=c"')
+# Strip symbols while compiling in release mode
+$([[ $@ =~ -r ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -Clink-arg=-s"')
+
+# Make sure that rust-bindgen uses the correct include path when cross-compiling
+# See https://github.com/rust-lang/rust-bindgen#environment-variables for more information
+ENV BINDGEN_EXTRA_CLANG_ARGS="-I\$TARGET_PREFIX/include"
+EOF
+
+# build conduit for a specific target
+cross build --target="$TARGET" $@