after input evaluation.

* lib/irb.rb (IRB::Irb::eval_input): untaint input string.  now
  irb works for levels 1 and 2.

* ext/syck/rubyext.c (syck_loader_transfer): should not use
  rb_cProc directly, since type_proc may be Proc, Block, or
  Method.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3931 b2dd03c8-39d4-4d8f-98ff-823fe69b080e