* gc.c: Use the non-recursive marking instead of recursion. The
  recursion marking of CRuby needs checking stack overflow and the
  fail-safe system, but these systems not good at partial points,
  for example, marking deep tree structures. [ruby-dev:46184]
  [Feature #7095]

* configure.in (GC_MARK_STACKFRAME_WORD): removed. It's used by
  checking stack overflow of marking.

* win32/Makefile.sub (GC_MARK_STACKFRAME_WORD): ditto.

* gc.c (free_stack_chunks): it is used only when per-VM object space
  is enabled.

* gc.c (rb_objspace_call_finalizer): mark self-referencing finalizers
  before run finalizers, to fix SEGV from btest on 32bit.

* gc.c (gc_mark_stacked_objects): extract from gc_marks().

* gc.c (rb_objspace_call_finalizer): call gc_mark_stacked_objects
  at suitable point.

* gc.c (init_heap): call init_mark_stack before to allocate
  altstack. This change avoid the stack overflow at the signal
  handler on 32bit, but I don't understand reason... [Feature #7095]



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@37648 b2dd03c8-39d4-4d8f-98ff-823fe69b080e