Complete the toolchain for linux-aarch64

In view of #12631 and #32355, after #41137 (closed), we should complete the toolchain for the linux-aarch64 target. As far cross-tools are concerned, this only amounts to building rust and clang, but clang already is a cross-compiler so it needs no special arrangements. The rest are host tools, which only require trivial changes. I'll submit a MR after #41137 (closed) is merged.