Ruby

• gc.c (gc_before_heap_sweep): fix freelist management.
  After rb_gc_force_recycle() for a object blonging to heap->freelist,
  `heap->using_page->freelist' is not null.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43421 b2dd03c8-39d4-4d8f-98ff-823fe69b080e