New comment by ahesford on void-packages repository

https://github.com/void-linux/void-packages/pull/28595#issuecomment-775393349

Comment:
If `setuptools_rust` upstream rejects the patch to honor RUSTFLAGS in the environment, either we patch anyway or we work around its tendency to overwrite that variable by wrapping `cargo` for cross builds of `python3-cryptography`:
```bash
pre_configure() {
	if [ "$CROSS_BUILD" ]; then
		cat > ${XBPS_WRAPPERDIR}/cargo <<-EOF
		#!/bin/bash
		if [[ ! "\$RUSTFLAGS" =~ "--sysroot" ]]; then
		    export RUSTFLAGS="\$RUSTFLAGS --sysroot=${XBPS_CROSS_BASE}/usr"
		fi
		exec /usr/bin/cargo "\$@"
		EOF
		chmod 755 ${XBPS_WRAPPERDIR}/cargo
	fi
}
```