dav1d-debian-unstable: Add cross-compiling toolchain for riscv64

dav1d-debian-unstable/Dockerfile

-FROM debian:sid-20230208-slim
+FROM debian:sid-20230411-slim
 
 MAINTAINER VideoLAN roots <roots@videolan.org>
 
@@ -19,14 +19,24 @@ RUN groupadd --gid ${VIDEOLAN_UID} videolan && \
     apt-get install --no-install-suggests --no-install-recommends -y \
         lftp ca-certificates curl git build-essential \
         nasm clang libclang-rt-dev mold meson ninja-build gcovr \
-        wine wine64 procps doxygen graphviz libsdl2-dev ripgrep && \
+        wine wine64 procps doxygen graphviz libsdl2-dev ripgrep \
+        debian-ports-archive-keyring && \
+    sed -i -e '$aArchitectures-Remove: riscv64' /etc/apt/sources.list.d/debian.sources && \
+    sed -e '/^URIs/c URIs: http://deb.debian.org/debian-ports' \
+        -e '/^Signed-By/c Signed-By: /usr/share/keyrings/debian-ports-archive-keyring.gpg' \
+        -e '/^Architectures/c Architectures: riscv64' \
+        /etc/apt/sources.list.d/debian.sources \
+        > /etc/apt/sources.list.d/debian-ports.sources && \
     dpkg --add-architecture i386 && \
+    dpkg --add-architecture riscv64 && \
     apt-get update && \
     apt-get install --no-install-suggests --no-install-recommends -y \
         gcc-mingw-w64-x86-64 g++-mingw-w64-x86-64 \
         gcc-mingw-w64-i686 g++-mingw-w64-i686 mingw-w64-tools \
         gcc-multilib g++-multilib \
         libc6-dev:i386 libgcc-12-dev:i386 wine32 qemu-user && \
+    apt-get install --no-install-suggests --no-install-recommends -y \
+        gcc-riscv64-linux-gnu g++-riscv64-linux-gnu libc6-dev:riscv64 && \
     apt-get clean -y && rm -rf /var/lib/apt/lists/*
 
 USER videolan