Use sched_yield on all POSIX platforms in PlatformThread.

Use sched_yield on all POSIX platforms in PlatformThread.
(not only MacOS)

This is a test to see if perf regressions we're seeing may be related to the use of nanosleep().

BUG=695438
TBR=solenberg@webrtc.org

Review-Url: https://codereview.webrtc.org/2716683002 .
Cr-Commit-Position: refs/heads/master@{#16807}
Committed: https://chromium.googlesource.com/external/webrtc/+/384498abb5a0dc3e871e437e56b4a556c3ec1023

[tommi, 2017-02-23 19:11:15]

The CQ bit was checked by tommi@webrtc.org

[commit-bot: I haz the power, 2017-02-23 19:11:18]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[tommi, 2017-02-23 19:23:25]

Description was changed from

==========
Use sched_yield on all POSIX platforms in PlatformThread.
(not only MacOS)

This is a test to see if perf regressions we're seeing may be related to the use
of nanosleep().

BUG=695438
TBR=solenberg@webrtc.org
==========

to

==========
Use sched_yield on all POSIX platforms in PlatformThread.
(not only MacOS)

This is a test to see if perf regressions we're seeing may be related to the use
of nanosleep().

BUG=695438
TBR=solenberg@webrtc.org

Review-Url: https://codereview.webrtc.org/2716683002 .
Cr-Commit-Position: refs/heads/master@{#16807}
Committed:
https://chromium.googlesource.com/external/webrtc/+/384498abb5a0dc3e871e437e5...
==========

[tommi, 2017-02-23 19:23:27]

Committed patchset #1 (id:1) manually as
384498abb5a0dc3e871e437e56b4a556c3ec1023 (presubmit successful).

[the sun, 2017-02-23 19:40:38]

lgtm

[tommi, 2017-02-24 17:12:18]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.webrtc.org/2712133003/ by tommi@webrtc.org.

The reason for reverting is: Reverting this change since it didn't affect the
perf regressions we were seeing and actually seems to have caused more
regressions as per comment in the bug..