tainted.

* ext/stringio/stringio.c (strio_copy, strio_ungetc, strio_write,
  strio_putc): add infection.

* ext/stringio/stringio.c (strio_path): just nil.  [ruby-dev:21846]

* ruby.c (proc_options): reserve searched script path in the
  source file name table.  [ruby-list:38765]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4906 b2dd03c8-39d4-4d8f-98ff-823fe69b080e