Fix thread safety of block out superseded flag, remove assert.

Author: evoskuil

include/bitcoin/node/protocols/protocol_block_out_70012.hpp

@@ -50,8 +50,8 @@ class BCN_API protocol_block_out_70012
         const network::messages::peer::send_headers::cptr& message) NOEXCEPT;
 
 private:
-    // This is protected by strand.
-    bool superseded_{};
+    // This is thread safe.
+    std::atomic_bool superseded_{};
 };
 
 } // namespace node

src/protocols/protocol_block_out_70012.cpp

@@ -65,7 +65,6 @@ bool protocol_block_out_70012::handle_receive_send_headers(const code& ec,
 // Suspends inventory announcement processing in favor of header announcements.
 bool protocol_block_out_70012::superseded() const NOEXCEPT
 {
-    BC_ASSERT(stranded());
     return superseded_;
 }