Revert of Use CLOCK_REALTIME_COARSE when available. (patchset #3 id:40001 of https://codereview.chromium.org/1125003002/)

Reason for revert:
[Sheriff] This causes layout test crashes:
http://build.chromium.org/p/client.v8/builders/V8-Blink%20Linux%2064%20%28dbg%29/builds/2735

You can add the trybot v8_linux_layout_dbg on reland.

Original issue's description:
> Use CLOCK_REALTIME_COARSE when available.
>
> On systems that have CLOCK_REALTIME_COARSE with good enough resolution, we can
> avoid making a system call to get the current time; it's serviced from the vDSO.
>
> BUG=
> LOG=N
>
> Committed: https://crrev.com/537ed7500c087786f28f51ff5222f1c2113776d3
> Cr-Commit-Position: refs/heads/master@{#28280}

TBR=jochen@chromium.org,deanm@chromium.org,bmeurer@chromium.org,ben@strongloop.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1130083003

Cr-Commit-Position: refs/heads/master@{#28288}