rb_str_dup_frozen()

* ruby.h: added declaration.
  rb_defout, rb_stdin, rb_stdout, rb_stderr, ruby_errinfo

* rubyio.h: changed double include guard macro to RUBYIO_H.

* array.c (inspect_call): make static.

* eval.c (dvar_asgn): ditto.

* io.c (rb_io_close_read): ditto.

* lex.c (rb_reserved_word): ditto.

* ruby.c: (req_list_head, req_list_last): ditto.

* ruby.c (require_libraries): ditto.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_6@1916 b2dd03c8-39d4-4d8f-98ff-823fe69b080e