io.c: get rid of IOError when skipped while iteration

* io.c (argf_close): deal with init flag.
* io.c (argf_block_call_i, argf_block_call): forward next file if
  skipped while iteration, to get rid of IOError.  [ruby-list:49185]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39996 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: get rid of IOError when skipped while iteration

* io.c (argf_next_argv): set init flag if succeeded to forward, after
  skipping.
* io.c (argf_block_call_i, argf_block_call): no more forwarding if
  forwarded after skipping.  [ruby-list:49185]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39997 b2dd03c8-39d4-4d8f-98ff-823fe69b080e