* gc.c (obj_id_to_ref): add a macro to treat Bignum object id.
	  This follows the change r38493.

	* gc.c (id2ref): fix for working fine with Bignum object id on x64
	  Windows.

	* gc.c (wmap_finalize): ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_3@38588 b2dd03c8-39d4-4d8f-98ff-823fe69b080e