Support pthread_{set,get}name_np for linux with glibc

[condy0919]

No description provided.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @gnzlbg (or someone else) soon.

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[gnzlbg]

@bors: r+

Thanks!

[bors]

📌 Commit 2686cc5 has been approved by gnzlbg

[bors]

⌛ Testing commit 2686cc5 with merge 54b03c5...

[bors]

☀️ Test successful - checks-cirrus-freebsd-11, checks-cirrus-freebsd-12, checks-travis, status-appveyor
Approved by: gnzlbg
Pushing 54b03c5 to master...