proc.c: Implement Method#curry

* proc.c (rb_method_curry): Implement Method#curry, which delegates
  to to_proc.curry.  [ruby-core:62212] [Feature #9783]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46461 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2014-06-19

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46462 b2dd03c8-39d4-4d8f-98ff-823fe69b080e