move the signal handler to the binary

src/bin/scryer-prolog.rs

@@ -9,3 +9,12 @@ fn main() {
     let mut wam = machine::Machine::new(readline::input_stream(), machine::Stream::stdout());
     wam.run_top_level();
 }
+
+pub extern "C" fn handle_sigint(signal: libc::c_int) {
+    use nix::sys::signal;
+    use std::sync::atomic::Ordering;
+    let signal = signal::Signal::from_c_int(signal).unwrap();
+    if signal == signal::Signal::SIGINT {
+        scryer_prolog::machine::INTERRUPT.store(true, Ordering::Relaxed);
+    }
+}