simple serenity build dockerfile

Dockerfile

FROM ubuntu:20.04

RUN apt update && \
    apt-get install software-properties-common wget -y

RUN apt-get purge -y gcc-9 g++-9 libstdc++-9-dev clang-format-10 && \
    wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | apt-key add - && \
    add-apt-repository "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-11 main" && \
    apt update && \
    apt install -y gcc-10 g++-10 clang-format-11 libstdc++-10-dev libmpfr-dev libmpc-dev ninja-build npm e2fsprogs qemu-system-i386 qemu-utils cmake

RUN update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 60 --slave /usr/bin/g++ g++ /usr/bin/g++-10