[RFC][PATCH] Move timekeeping code to timekeeping.c

So I've been putting off this change for awhile since there's been so much churn in the timekeeping code, but now looking at both -mm and -rt it seems there is only a minimal amount of timekeeping changes pending, so I wanted to send this out there for comments before pushing it to -mm

[RFC][PATCH] Move timekeeping code to timekeeping.c

So I've been putting off this change for awhile since there's been so much churn in the timekeeping code, but now looking at both -mm and -rt it seems there is only a minimal amount of timekeeping changes pending, so I wanted to send this out there for comments before pushing it to -mm