/usr/i686-linux-gnu/include/linux/tc_act/ is in linux-libc-dev-i386-cross 4.15.0-18.19cross1.
This file is owned by root:root, with mode 0o755.
..
/usr/i686-linux-gnu/include/linux/tc_act/tc_bpf.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_connmark.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_csum.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_defact.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_gact.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_ife.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_ipt.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_mirred.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_nat.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_pedit.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_sample.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_skbedit.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_skbmod.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_tunnel_key.h
/usr/i686-linux-gnu/include/linux/tc_act/tc_vlan.h