/usr/include/varnish/tbl/ is in libvarnishapi-dev 5.2.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/varnish/tbl/acct_fields_bereq.h
/usr/include/varnish/tbl/acct_fields_req.h
/usr/include/varnish/tbl/backend_poll.h
/usr/include/varnish/tbl/ban_vars.h
/usr/include/varnish/tbl/bo_flags.h
/usr/include/varnish/tbl/boc_state.h
/usr/include/varnish/tbl/body_status.h
/usr/include/varnish/tbl/cli_cmds.h
/usr/include/varnish/tbl/debug_bits.h
/usr/include/varnish/tbl/feature_bits.h
/usr/include/varnish/tbl/h2_error.h
/usr/include/varnish/tbl/h2_frames.h
/usr/include/varnish/tbl/h2_settings.h
/usr/include/varnish/tbl/h2_stream.h
/usr/include/varnish/tbl/http_headers.h
/usr/include/varnish/tbl/http_response.h
/usr/include/varnish/tbl/locks.h
/usr/include/varnish/tbl/obj_attr.h
/usr/include/varnish/tbl/oc_exp_flags.h
/usr/include/varnish/tbl/oc_flags.h
/usr/include/varnish/tbl/params.h
/usr/include/varnish/tbl/req_body.h
/usr/include/varnish/tbl/req_flags.h
/usr/include/varnish/tbl/sess_attr.h
/usr/include/varnish/tbl/sess_close.h
/usr/include/varnish/tbl/steps.h
/usr/include/varnish/tbl/symbol_kind.h
/usr/include/varnish/tbl/vcc_types.h
/usr/include/varnish/tbl/vcl_returns.h
/usr/include/varnish/tbl/vhd_fsm.h
/usr/include/varnish/tbl/vhd_fsm_funcs.h
/usr/include/varnish/tbl/vhd_return.h
/usr/include/varnish/tbl/vhp_huffman.h
/usr/include/varnish/tbl/vhp_static.h
/usr/include/varnish/tbl/vrt_stv_var.h
/usr/include/varnish/tbl/vsc_levels.h
/usr/include/varnish/tbl/vsl_tags.h
/usr/include/varnish/tbl/vsl_tags_http.h
/usr/include/varnish/tbl/waiters.h