marshal.c: revert r57631 partially

	* marshal.c (rb_marshal_dump_limited): do not free dump_arg, which
	  may be dereferenced in check_dump_arg due to continuation, and
	  get rid of dangling pointers.

	* marshal.c (rb_marshal_load_with_proc): ditto for load_arg.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@59551 b2dd03c8-39d4-4d8f-98ff-823fe69b080e