CI script fails on Redox build
Recent Redox CI builds of relibc fail with the following error:
[...]
$ export PATH="$PWD/prefix/bin:$PATH"
$ export RUSTUP_TOOLCHAIN="$PWD/prefix"
$ cargo install xargo
cargo: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.25' not found (required by cargo)
ERROR: Job failed: exit code 1
(The Linux build still succeeds.)