rust/chg/build.rs

revlog: prepare pure parser for being overloaded

The current class uses module-level variables which don't allow for reusing the
current logic for a slightly different revlog version.

Differential Revision: https://phab.mercurial-scm.org/D9903

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