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");
}