Precompiled binaries of version-specific tools required for working with the GCC source code.
You can download the prebuilt tools from the releases page:
cd /tmp
wget https://github.com/AmanoTeam/gcc-tools/releases/download/rolling/x86_64-unknown-linux-gnu.tar.xz
tar xf x86_64-unknown-linux-gnu.tar.xz
export LD_LIBRARY_PATH=/tmp/autotools/lib