* hash.c: `st_update()' also has same issue of last fix.
  write barriers at callback function are too early.
  All write barriers are executed after `st_update()'



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41398 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* vm.c (kwmerge_i): add WB.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41399 b2dd03c8-39d4-4d8f-98ff-823fe69b080e