The `--tos` flag is ignored for IPv4/UDP

[fujiapple852]

Describe the bug

The --tos (-Q) flag is ignored for IPv4/UDP.

This flag is intended to set the IP_TOS TOS (DSCP+ECN) socket option for UDP and TCP.

The feature was first added in 9bf3825 but has since regressed.

The flag works as expected for IPv4/TCP.