revlog: allow to pass an existing docket to `_loadindex()` This will be when switching undelying files, for examples during censors and strip operation with rvlog-v2. Differential Revision: https://phab.mercurial-scm.org/D10800

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