8261652: Remove some dead comments from os_bsd_x86

[VladimirKempik]

This is a backport of 8261652.
This patch removes some dead comment about older macos and removes double inclusion of pthread.h
Comment location is slightly different from jdk17, but since it is a comment I would call this effectively clean backport.
This is a soft prerequest for macarm.

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8261652: Remove some dead comments from os_bsd_x86

Reviewers

• Paul Hohensee (@phohensee - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk11u-dev pull/11/head:pull/11
$ git checkout pull/11

Update a local copy of the PR:
$ git checkout pull/11
$ git pull https://git.openjdk.java.net/jdk11u-dev pull/11/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 11

View PR using the GUI difftool:
$ git pr show -t 11

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk11u-dev/pull/11.diff

[bridgekeeper]

👋 Welcome back vkempik! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

@VladimirKempik This change now passes all automated pre-integration checks.

After integration, the commit message for the final commit will be:

8261652: Remove some dead comments from os_bsd_x86

Reviewed-by: phh

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

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[mlbridge]

Webrevs

• 00: Full (0f2f2c04)

[VladimirKempik]

/integrate

[openjdk]

@VladimirKempik Since your change was applied there has been 1 commit pushed to the master branch:

• 09d3082: 8265231: (fc) ReadDirect and WriteDirect tests fail after fix for JDK-8264821

Your commit was automatically rebased without conflicts.

Pushed as commit ab9d3de.

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