src: Silence compiler warning

src/asio_http2_handler.cc

@@ -827,6 +827,11 @@ int http2_handler::push_promise(http2_stream& stream, std::string method,
   return 0;
 }
 
+boost::asio::io_service& http2_handler::io_service()
+{
+  return io_service_;
+}
+
 callback_guard::callback_guard(http2_handler& h)
   : handler(h)
 {

src/asio_http2_handler.h

@@ -165,6 +165,8 @@ public:
                    std::string path,
                    std::vector<header> headers);
 
+  boost::asio::io_service& io_service();
+
   template<size_t N>
   int on_read(const boost::array<uint8_t, N>& buffer, std::size_t len)
   {