unix: add unix.TimeToPtpClockTime on Linux

[yarikk]

Add time conversion helpers for PtpClockTime similar to those
existing for Timespec and Timeval.

Allows to use the maths of the standard time package while avoiding
the boilerplate:
write "ptpt.Time()" instead of "time.Unix(ptpt.Sec, int64(ptpt.Nsec))",
and "unix.TimeToPtpClockTime(t)" instead of
"unix.PtpClockTime{Sec: t.Unix(), Nsec: uint32(t.Nanosecond())}".

Fixes golang/go#70032

[gopherbot]

This PR (HEAD: 57a5a04) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/sys/+/621498.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Gopher Robot:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Yaroslav Kolomiiets:

Patch Set 1:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 1: Commit-Queue+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 1:

Dry run: CV is trying the patch.

Bot data: {"action":"start","triggered_at":"2024-10-22T22:45:28Z","revision":"d5b6ecbfb75bb555c21c2565098eaf833d8b06ab"}

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 1: -Commit-Queue

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 1:

This CL has passed the run

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Go LUCI:

Patch Set 1: LUCI-TryBot-Result+1

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 1:

(2 comments)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR (HEAD: 975cf14) has been imported to Gerrit for code review.

Please visit Gerrit at https://go-review.googlesource.com/c/sys/+/621498.

Important tips:

• Don't comment on this PR. All discussion takes place in Gerrit.
• You need a Gmail or other Google account to log in to Gerrit.
• To change your code in response to feedback:
  • Push a new commit to the branch used by your GitHub PR.
  • A new "patch set" will then appear in Gerrit.
  • Respond to each comment by marking as Done in Gerrit if implemented as suggested. You can alternatively write a reply.
  • Critical: you must click the blue Reply button near the top to publish your Gerrit responses.
  • Multiple commits in the PR will be squashed by GerritBot.
• The title and description of the GitHub PR are used to construct the final commit message.
  • Edit these as needed via the GitHub web interface (not via Gerrit or git).
  • You should word wrap the PR description at ~76 characters unless you need longer lines (e.g., for tables or URLs).
• See the Sending a change via GitHub and Reviews sections of the Contribution Guide as well as the FAQ for details.

[gopherbot]

Message from Yaroslav Kolomiiets:

Patch Set 2:

(2 comments)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 2:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Yaroslav Kolomiiets:

Patch Set 2:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 3: Hold+1

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Yaroslav Kolomiiets:

Patch Set 3:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Ian Lance Taylor:

Patch Set 3:

(1 comment)

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/621498.
After addressing review feedback, remember to publish your drafts!