Increment SESSION_COUNT when cloning a Session.

Fixes #8166.

Author: fuzyll

rust/src/headless.rs

@@ -422,6 +422,15 @@ impl Session {
     }
 }
 
+impl Clone for Session {
+    fn clone(&self) -> Self {
+        SESSION_COUNT.fetch_add(1, SeqCst);
+        Self {
+            license_duration: self.license_duration,
+        }
+    }
+}
+
 impl Drop for Session {
     fn drop(&mut self) {
         let previous_count = SESSION_COUNT.fetch_sub(1, SeqCst);