This is necessary for the pthread_attr_get_np function.

Change-Id: I01cfe075a7c86909e8cf37eb7f7c5d44fa044975
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2188310
Commit-Queue: Michaël Zasso <mic.besace@gmail.com>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Michaël Zasso <mic.besace@gmail.com>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67660}