merge revision(s) r46501,r47372,r47460: [Backport #10191]

	* object.c (rb_obj_copy_ivar): extract function to copy instance
	  variables only for T_OBJECT from init_copy.

	* object.c (rb_obj_copy_ivar): allocate no memory for empty
	  instance variables.  [ruby-core:64700] [Bug #10191]

	* test/ruby/test_object.rb: extend timeout.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47520 b2dd03c8-39d4-4d8f-98ff-823fe69b080e