* array.c (rb_to_array_type): make public to share common code
  internally.

* hash.c (rb_to_hash_type): make public to share common code
  internally.

* symbol.c (rb_to_symbol_type): make public to share common code
  internally.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60438 b2dd03c8-39d4-4d8f-98ff-823fe69b080e