sched: add [__]update_rq_clock(rq)

add the [__]update_rq_clock(rq) functions. (No change in functionality,
just reorganization to prepare for elimination of the heavy 64-bit
timestamp-passing in the scheduler.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --cc kernel/sched.c
Simple merge