Impact: extend information in /proc/sched_debug

This patch adds uid information in sched_debug for CONFIG_USER_SCHED
Signed-off-by: NArun R Bharadwaj <arun@linux.vnet.ibm.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>