Ruby

variable.c: extract common functions for generic ivar indices

• variable.c (iv_index_tbl_make): extract from rb_ivar_set
  (iv_index_tbl_extend): ditto
  (iv_index_tbl_newsize): ditto
  (rb_ivar_set): use extracted functions
  [ruby-core:69323] (Part 1)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50676 b2dd03c8-39d4-4d8f-98ff-823fe69b080e