Ruby

Fix running GC in finalizer when RUBY_FREE_AT_EXIT

The following code crashes because the GC ran during finalizers will
cause T_ZOMBIE objects to be on the heap, which crashes when we call
rb_gc_obj_free on it:

raise_proc = proc do |id|
  GC.start
end
1000.times do
  ObjectSpace.define_finalizer(Object.new, raise_proc)
end