runtime: disable preemption in several scheduler functions Required for preemptive scheduler, see the comments for details.
runtime: disable preemption in several scheduler functions
Required for preemptive scheduler, see the comments for details.

R=golang-dev, khr, iant, khr
CC=golang-dev
https://codereview.appspot.com/9740051

wesolows/golang-old,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang,wesolows/golang,wesolows/golang-old,wesolows/golang,wesolows/golang