[CVS ci] better DOD profiling

[Leopold Toetsch]

I've divided the profile counters for DOD into 4. We now have:

$ parrot -p tools/dev/bench_op.imc 'new $P0, .PerlInt'
...
   -4  DOD_collect_PMC            51    0.007713      0.1512
   -3  DOD_collect_buffers        51    0.003491      0.0685
   -5  DOD_mark_next              51    0.003178      0.0623
   -6  DOD_mark_root              51    0.002942      0.0577
...
DOD_mark_next is mark phase 2: marking through next_for_GC pointers.

leo