Arm64 docker image for cross compiling

[banderson-syd]

Feature Description

Hello and thank you all for the incredible hard work that you've done to make Slint such an amazing development experience.
I was testing out cross compilation for Slint using the provided docker images and saw that the image for armv7-unknown-linux-gnueabihf was set to compile as Arm32, with the note that the base image should be switched to the rustembedded/cross:armv7-unknown-linux-gnueabihf-0.2.1 image once this merge request is merged and released. It looks like this has indeed been taken care of now, so this is a note that I believe we can now make use of the Arm64 image with something to the effect of:

FROM rustembedded/cross:armv7-unknown-linux-gnueabihf-0.2.1

RUN dpkg --add-architecture arm64 && \
    apt-get update && \
    DEBIAN_FRONTEND=noninteractive apt-get install --assume-yes libfontconfig1-dev:arm64 libxcb1-dev:arm64 libxcb-render0-dev:arm64 libxcb-shape0-dev:arm64 libxcb-xfixes0-dev:arm64 libxkbcommon-dev:arm64 libinput-dev:arm64 libgbm-dev:arm64 libssl-dev:arm64 python3 python3-pip \
    libfontconfig1-dev \
    clang libstdc++-10-dev:arm64 \ 

RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
    apt-get install --assume-yes software-properties-common && \
    add-apt-repository -y ppa:git-core/ppa && \
    apt-get install --assume-yes git && \
    git config --global safe.directory '*'

ENV PKG_CONFIG_PATH=/usr/lib/arm-linux-gnueabihf/pkgconfig
ENV PKG_CONFIG_ALLOW_CROSS=1
ENV BINDGEN_EXTRA_CLANG_ARGS_armv7_unknown_linux_gnueabihf=-I/usr/include

The stdc++-10-dev:arm64 package doesn't exist, I believe the package that we're looking for would be libstdc++-10-dev-arm64-cross, but the base image seems to be unable to locate that package, so I would be interested to hear if there was an alternative anyone was familiar with so that we could do Arm64 cross compilation with this docker image for Slint. Thank you all again!

Product Impact

No response