object, if b has "to_ary" and b == a.
* hash.c (rb_hash_equal): a == b is true when b is non T_HASH
object, if b has "to_hash" and b == a.
* string.c (rb_str_equal): a == b is true when b is non T_STRING
object, if b has "to_str" and b == a.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3442 b2dd03c8-39d4-4d8f-98ff-823fe69b080e