* gc.c (CALC_EXACT_MALLOC_SIZE_CHECK_OLD_SIZE): introduced.
  This macro enable checker compare with allocated memory and
  declared old_size of sized_xfree and sized_xrealloc.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43336 b2dd03c8-39d4-4d8f-98ff-823fe69b080e