Add a C++ friendly docker build file

This takes an existing cross-friendly image and adds cmake, ninja, cargo,
and rust. It also enables dlopen linkage for the compiler.

.github/workflows/embedded_build.yaml

@@ -30,12 +30,21 @@ jobs:
         username: ${{ github.actor }}
         password: ${{ secrets.CR_PAT }}
     - name: Build and push
-      uses: docker/build-push-action@v2
+      uses: docker/build-push-action@v3
       with:
         context: .
         file: ./docker/Dockerfile.${{ matrix.target }}
         push: true
         tags: ghcr.io/slint-ui/slint/${{matrix.target}}:latest
+    - name: Build and push C++ image
+      uses: docker/build-push-action@v3
+      with:
+        context: .
+        file: ./docker/Dockerfile.cpp-image
+        push: true
+        tags: ghcr.io/slint-ui/slint/${{matrix.target}}-cpp:latest
+        build-args:
+          - ARCH=${{matrix.target}}
 
   build:
     needs: [build_containers]

docker/Dockerfile.cpp-image

@@ -0,0 +1,21 @@
+ARG arch
+FROM ghcr.io/slint-ui/slint/$arch
+ARG arch
+
+RUN apt-get update && \
+    apt-get install --assume-yes gpg wget && \
+    wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | tee /usr/share/keyrings/kitware-archive-keyring.gpg >/dev/null && \
+    echo 'deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ focal main' | tee /etc/apt/sources.list.d/kitware.list >/dev/null && \
+    apt-get update && \
+    apt-get install --assume-yes cmake ninja-build make && \
+    rm -rf /var/lib/apt/lists/*
+
+
+ENV RUSTUP_HOME=/rust
+ENV CARGO_HOME=/cargo 
+ENV PATH=/cargo/bin:/rust/bin:$PATH
+
+RUN curl https://sh.rustup.rs -sSf | sh -s -- -y
+RUN rustup target add $arch
+
+ENV RUST_FONTCONFIG_DLOPEN=on