Renable...

docker/Dockerfile_x86_ffmpeg

@@ -5,11 +5,11 @@ RUN apt-get update
 
 RUN apt-get install -y curl git pkg-config yasm
 RUN apt-get install -y build-essential clang
-# RUN apt-get install -y musl-tools musl-dev musl
+RUN apt-get install -y musl-tools musl-dev musl
 
 RUN curl https://sh.rustup.rs -sSf | sh -s -- -y
 ENV PATH="/root/.cargo/bin/:${PATH}"
-# RUN rustup target add x86_64-unknown-linux-musl
+RUN rustup target add x86_64-unknown-linux-musl
 
 RUN mkdir /build
 ENV CARGO_TARGET_DIR /build