Adding TEMP_FAILURE_RETRY definition for musl

[foopub]

Needed to compile under musl. Taken directly from glibc's unistd.h:
https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=posix/unistd.h;hb=HEAD

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[foopub]

@philwo fix for #12460

[foopub]

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On Mon, May 17, 2021 at 7:12 PM google-cla[bot] ***@***.***> wrote: Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA). 📝 *Please visit https://cla.developers.google.com/ <https://cla.developers.google.com/> to sign.* Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it. ------------------------------ What to do if you already signed the CLA Individual signers - It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data <https://cla.developers.google.com/clas> and verify that your email is set on your git commits <https://help.github.com/articles/setting-your-email-in-git/>. Corporate signers - Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version <https://opensource.google/docs/cla/#troubleshoot>). - The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data <https://cla.developers.google.com/clas> and verify that your email is set on your git commits <https://help.github.com/articles/setting-your-email-in-git/>. - The email used to register you as an authorized contributor must also be attached to your GitHub account <https://github.com/settings/emails>. ℹ️ *Googlers: Go here <https://goto.google.com/prinfo/https%3A%2F%2Fgithub.com%2Fbazelbuild%2Fbazel%2Fpull%2F13483> for more info*. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#13483 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AK22V6I46JDMM4MBH6SAMDLTOFL7VANCNFSM45A6O7UQ> .

[aiuto]

Is there an existing issue that this fixes?

[philwo]

@foopub Thanks! I need to clarify something internally first, but should get an answer today, I'll follow up here asap.

[philwo]

Hi @foopub, sorry for the delay. The problem is that we can't accept a patch that is copying or based on glibc's code due to licensing issues. I know it's just a small snippet, but we really want to be careful here and do the right thing. 😊

The good news is that I found an internal source for this macro in our Google repo and can just use that one instead. I'm sorry for the hassle and hope for your understanding!

I'll tag #12460 in my commit so you'll see when it's committed!