* vm_args.c (setup_parameters_complex): don't raise ArgumentError
	  if an array is given for instance_exec with optional argument.
	  [ruby-core:76300] [Bug #12568]
	  https://github.com/rails/rails/pull/25699


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@55956 b2dd03c8-39d4-4d8f-98ff-823fe69b080e