fix FreeBSD build (#249)

* update boringtun dependency

* remove unused method

Author: wojcik91

Cargo.lock

@@ -327,19 +327,6 @@ impl Pool {
 
         unsafe { uninit.assume_init() }
     }
-
-    /// Insert `PoolAddr` at the end of the list. Take ownership of the given `PoolAddr`.
-    pub(super) fn insert_pool_addr(&mut self, mut pool_addr: PoolAddr) {
-        // TODO: Traverse tail queue; for now assume empty tail queue.
-        assert!(
-            self.list.tqh_first.is_null(),
-            "Expected one entry in PoolAddr TailQueue."
-        );
-        self.list.tqh_first = &raw mut pool_addr;
-        self.list.tqh_last = &raw mut pool_addr.entries.tqe_next;
-        pool_addr.entries.tqe_next = ptr::null_mut();
-        pool_addr.entries.tqe_prev = &raw mut self.list.tqh_first;
-    }
 }
 
 impl Drop for Pool {