Add int return value to nghttp2_on_frame_recv_callback
Add int return value to nghttp2_on_invalid_frame_recv_callback
Add int return value to nghttp2_on_data_chunk_recv_callback
Add int return value to nghttp2_on_data_recv_callback
Add int return value to nghttp2_before_frame_send_callback
Add int return value to on_frame_send_callback
Add int return value to on_frame_not_send_callback
Add int return value to on_data_send_callback
Add int return value to nghttp2_on_stream_close_callback
Add int return value to nghttp2_on_request_recv_callback
Add int return value to nghttp2_on_frame_recv_parse_error_callback
Add int return value to nghttp2_on_unknown_frame_recv_callback
nghttp: Fix off-by-one error when allocating space for request headers