Refactoring and tidy up

This is a port of some of the changes from my private local-GC branch
(which is still in darcs, I haven't converted it to git yet).  There
are a couple of small functional differences in the GC stats: first,
per-thread GC timings should now be more accurate, and secondly we now
report average and maximum pause times. e.g. from minimax +RTS -N8 -s:

                                    Tot time (elapsed)  Avg pause  Max pause
  Gen  0      2755 colls,  2754 par   13.16s    0.93s     0.0003s    0.0150s
  Gen  1       769 colls,   769 par    3.71s    0.26s     0.0003s    0.0059s

1 files changed, 1 insertions, 0 deletions

diff --git a/rts/Schedule.h b/rts/Schedule.h
index edba8f5f16..549f555a11 100644
--- a/rts/Schedule.h
+++ b/rts/Schedule.h
@@ -23,6 +23,7 @@
 void initScheduler (void);
 void exitScheduler (rtsBool wait_foreign);
 void freeScheduler (void);
+void markScheduler (evac_fn evac, void *user);
 
 // Place a new thread on the run queue of the current Capability
 void scheduleThread (Capability *cap, StgTSO *tso);