Ruby

vm_insnhelper.c: no splat single opt arg

• vm_insnhelper.c (vm_yield_setup_block_args): pass single argument to
  single optional parameter unchanged without splatting. [Bug #7621]
  [ruby-dev:46801]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38639 b2dd03c8-39d4-4d8f-98ff-823fe69b080e