ci: avoid a global before_script definition This removes the implicit assumption that all jobs are test runs. Differential Revision: https://phab.mercurial-scm.org/D9723

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