TS-1006: Fix double-linked list initialization in reclaimable_freelist_new

This bug broke the double-linked list which would prevent self-thread
"stealing" memory from other threads. It was found by Weijin when he
reviewed the code, thans a lot!

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
Signed-off-by: Zhao Yongming <ming.zym@gmail.com>