rust/chg/build.rs

tests: show that in-memory rebase leaves state when working copy is dirty

When in-memory rebase falls back to on-disk rebase, it checks if the
working copy is dirty. If it is, it aborts the rebase. However, it
leaves the rebase state on disk. I broke it in feffeb18d412 (rebase:
teach in-memory rebase to not restart with on-disk rebase on conflict,
2020-09-18).

Differential Revision: https://phab.mercurial-scm.org/D9508

fn main() {
    cc::Build::new()
        .warnings(true)
        .file("src/sendfds.c")
        .file("src/sighandlers.c")
        .compile("procutil");
}