[LITMUS^RT] Bugfix: make sure rq->clock is current

[Björn Brandenburg]

Hi everyone,

I've come across a case where the "precise" budget enforcement wasn't actually all that precise because the underlying time-tracking was using stale timestamps. I've pushed a patch to staging to fix this.

	https://github.com/LITMUS-RT/litmus-rt/commit/b03f803a931226b0bf15e8bf4c18fa508ac9ff49	
Please let me know should this cause any problems.

Thanks,
Björn