Update first_pending_io, schannel fix (#663)

* Update first_pending_io

* Fix 2

adapters/tlsio_schannel.c

@@ -765,6 +765,8 @@ static void on_underlying_io_bytes_received(void* context, const unsigned char*
                                             indicate_error(tls_io_instance);
                                         }
                                     }
+
+                                    first_pending_io = singlylinkedlist_get_head_item(tls_io_instance->pending_io_list);
                                 }
                             }
                         }
@@ -1241,6 +1243,8 @@ void tlsio_schannel_destroy(CONCRETE_IO_HANDLE tls_io)
                 {
                     LogError("Failure: removing pending IO from list");
                 }
+
+                first_pending_io = singlylinkedlist_get_head_item(tls_io_instance->pending_io_list);
             }
         }