[PORT FROM R4]sched: Set skip_clock_update in yield_task_fair()

[PORT FROM R4]sched: Set skip_clock_update in yield_task_fair()

BZ: 42195

(backport of upstream commit 916671c08, merged in v3.3-rc1)

This is another case where we are on our way to schedule(),
so can save a useless clock update and resulting microscopic
vruntime update.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1321971686.6855.18.camel@marge.simson.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Change-Id: I55962c20a65857f52566c1970cb02e27f82845a8
Orig-Change-Id: I9e0b31ea4008cb0ed84b1dd3739c401856fdac4d
Signed-off-by: German Monroy <german.monroy@intel.com>
Reviewed-on: http://android.intel.com:8080/54410
Reviewed-by: Yang, Fei <fei.yang@intel.com>
Tested-by: Ng, Cheon-woei <cheon-woei.ng@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>