* gc.c: refactoring GC::Profiler.
* gc.c (gc_prof_sweep_timer_start/stop): removed because
  they doesn't support lazy sweep.
* gc.c (gc_prof_sweep_slot_timer_start/stop): added.
  redefine `sweeping time' to accumulated time of all of
  slot_sweep().
* gc.c (rb_objspace_t::profile::count): renamed to
  rb_objspace_t::profile::next_index. `counter' seems ambiguous.
  increment it when next record is acquired.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40700 b2dd03c8-39d4-4d8f-98ff-823fe69b080e