gc.c: fix build with RGENGC_ESTIMATE_OLDMALLOC=0

	* gc.c (gc_info_decode): Fix build errors wheb compiled with
	  RGENGC_ESTIMATE_OLDMALLOC=0
	* gc.c (objspace_malloc_increase): ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44225 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-12-16

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44226 b2dd03c8-39d4-4d8f-98ff-823fe69b080e