external/bb_segment/bb_compute_l.h缺少头文件

应该加上
```
#include "bb_comput_s.h"
#include "bb_exch.h"
```
不然会产生
`tSparse/tSparse-src/external/bb_segsort/bb_comput_s.h(312): error: type name is not allowed detected during: instantiation of "int bb_segsort(K *, T *, int, int *, int, K *, T *) [with K=int, T=int]"`
的错误