Ruby » Ruby master

• gc.c: move immutable fields from struct heaps_slot and struct
  sorted_heaps_slot into struct heaps_header.
  Based on a patch from Sokolov Yura [Feature #6199][ruby-core:43592]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37613 b2dd03c8-39d4-4d8f-98ff-823fe69b080e