upstream: Deprecate support for IPv4 type-of-service (TOS) IPQoS

upstream: Deprecate support for IPv4 type-of-service (TOS) IPQoS

keywords

Type of Service (ToS) was deprecated in the late nineties and replaced
with the Differentiated Services architecture. Diffserv has significant
advantages for operators because this mechanism offers more granularity.

OpenSSH switched its default IPQoS from ToS to DSCP values in 2018.

IPQoS configurations with 'lowdelay', 'reliability', or 'throughput' will be
ignored and instead the system default QoS settings apply. Additionally, a
debug message is logged about the deprecation with a suggestion to use DSCP.

with/OK deraadt@ sthen@ djm@

OpenBSD-Commit-ID: 40c8c0c5cb20151a348728703536af2ec1c754ba