ccccf94fb5
Track relibc submodule at the epoll_ctl transient-retry fix (415fa3c8),
which lets tokio runtimes (the zbus daemons and the brush login shell)
build past the transient /scheme/event EINVAL/EBADF during early-boot
scheme churn.
redbear-bare.toml: switch [users.root]/[users.user] to /usr/bin/brush and
add the brush package, so bare and mini share an identical boot-to-login
shell (bare = minimal boot-test surface, mini = +app payload).