Proper ctrl+c handling in Windows (fix #508)

src/ctrlc/interrupted.rs

@@ -0,0 +1,22 @@
+use lazy_static::lazy_static;
+use std::sync::atomic::{AtomicBool, Ordering};
+
+lazy_static! {
+    /// A global variable telling whether the application has been interrupted.
+    static ref INTERRUPTED: AtomicBool = AtomicBool::new(false);
+}
+
+/// Tells whether the program has been interrupted
+pub fn interrupted() -> bool {
+    INTERRUPTED.load(Ordering::SeqCst)
+}
+
+/// Clears the interrupted flag
+pub fn unset_interrupted() {
+    debug_assert!(INTERRUPTED.load(Ordering::SeqCst));
+    INTERRUPTED.store(false, Ordering::SeqCst)
+}
+
+pub fn set_interrupted() {
+    INTERRUPTED.store(true, Ordering::SeqCst)
+}