OpenBSD pflog adds some fields which aren't present in FreeBSD,
as a result the packet's padding is different.

The DHCPv4 header field "HardwareOpts" is misleading. This fields
original name by RFC 2131, which just takes it from RFC 951, is "hops".
It has never changed meaning and still reflects number of relay agents
it passed, as described in RFC 951 section 8.

This commit changes the name of the field "HardwareOpts" to "RelayHops".

* Add DHCPv4 no options test

* Fix DHCPv4 options encoding

For calculating the DHCPv4 length by the "Len" method there is always a
byte added for the end option. But the END option is only set when there
are any options at all. This results in a missing END option in case
there are no options present.

This commit moves the encoding of the END option so it is always set
unconditionally.

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Bumps [golang.org/x/net](https://github.com/golang/net) from 0.7.0 to 0.17.0.
- [Commits](golang/net@v0.7.0...v0.17.0)

---
updated-dependencies:
- dependency-name: golang.org/x/net
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Some metadata arrays are pretty big (e.g. `EthernetTypeMetadata` has
65536 slots), while only a small subset of the values are filled with
actual decoders (e.g. for `EthernetTypeMetadata` that is 18 entries).

The rest were filled in `func init()` to return error on access. This
leads to noticeable startup time delay, as these mappings are pretty
big.

This change simply leaves not used slots unset (zero value), and the
request error values are generated on access to the slot.

Comparing time with `GODEBUG=inittrace=1` on a simple test program which
imports `gopacket/layers`:

before:

```
init internal/bytealg @0 ms, 0 ms clock, 0 bytes, 0 allocs
init runtime @0.009 ms, 0.063 ms clock, 0 bytes, 0 allocs
init math @0.18 ms, 0 ms clock, 0 bytes, 0 allocs
init errors @0.19 ms, 0 ms clock, 0 bytes, 0 allocs
init sync @0.20 ms, 0.002 ms clock, 16 bytes, 1 allocs
init internal/godebug @0.21 ms, 0.020 ms clock, 816 bytes, 20 allocs
init internal/intern @0.23 ms, 0.002 ms clock, 408 bytes, 8 allocs
init hash/crc32 @0.24 ms, 0.008 ms clock, 1024 bytes, 1 allocs
init net/netip @0.26 ms, 0 ms clock, 48 bytes, 2 allocs
init syscall @0.26 ms, 0.003 ms clock, 640 bytes, 3 allocs
init time @0.27 ms, 0.002 ms clock, 0 bytes, 0 allocs
init context @0.28 ms, 0 ms clock, 96 bytes, 1 allocs
init io/fs @0.29 ms, 0 ms clock, 0 bytes, 0 allocs
init os @0.30 ms, 0.006 ms clock, 328 bytes, 7 allocs
init unicode @0.31 ms, 0 ms clock, 512 bytes, 4 allocs
init reflect @0.32 ms, 0 ms clock, 0 bytes, 0 allocs
init vendor/golang.org/x/net/dns/dnsmessage @0.32 ms, 0.002 ms clock, 624 bytes, 6 allocs
init net @0.33 ms, 0.002 ms clock, 688 bytes, 13 allocs
init github.com/gopacket/gopacket @0.34 ms, 0.003 ms clock, 720 bytes, 5 allocs
init github.com/gopacket/gopacket/layers @0.35 ms, 1.3 ms clock, 25136 bytes, 63 allocs
```

after:

```
init internal/bytealg @0 ms, 0 ms clock, 0 bytes, 0 allocs
init runtime @0.011 ms, 0.070 ms clock, 0 bytes, 0 allocs
init math @0.26 ms, 0 ms clock, 0 bytes, 0 allocs
init errors @0.27 ms, 0 ms clock, 0 bytes, 0 allocs
init sync @0.27 ms, 0.003 ms clock, 16 bytes, 1 allocs
init internal/godebug @0.28 ms, 0.023 ms clock, 816 bytes, 20 allocs
init internal/intern @0.31 ms, 0.002 ms clock, 408 bytes, 8 allocs
init hash/crc32 @0.32 ms, 0.008 ms clock, 1024 bytes, 1 allocs
init net/netip @0.33 ms, 0 ms clock, 48 bytes, 2 allocs
init syscall @0.34 ms, 0.003 ms clock, 640 bytes, 3 allocs
init time @0.35 ms, 0.003 ms clock, 0 bytes, 0 allocs
init context @0.37 ms, 0 ms clock, 96 bytes, 1 allocs
init io/fs @0.38 ms, 0 ms clock, 0 bytes, 0 allocs
init os @0.38 ms, 0.009 ms clock, 328 bytes, 7 allocs
init unicode @0.40 ms, 0 ms clock, 512 bytes, 4 allocs
init reflect @0.41 ms, 0 ms clock, 0 bytes, 0 allocs
init vendor/golang.org/x/net/dns/dnsmessage @0.42 ms, 0.002 ms clock, 624 bytes, 6 allocs
init net @0.43 ms, 0.004 ms clock, 688 bytes, 13 allocs
init github.com/gopacket/gopacket @0.44 ms, 0.003 ms clock, 720 bytes, 5 allocs
init github.com/gopacket/gopacket/layers @0.46 ms, 0.086 ms clock, 25872 bytes, 66 allocs
```

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>