libunwind build latex2man: Command not found

docker 环境, images: centos:7 编译环境为centos 7 自带的Development Tools group
```dockerfile
FROM centos:latest
MAINTAINER ystyle "lxy5266@live.com"
RUN yum -y groupinstall 'Development Tools'
RUN yum -y install zlib-devel wget fuse git
RUN cd / && git clone https://github.com/baidu/bfs.git
RUN yum -y install libunwind-devel libunwind cmake
RUN cd /bfs && ./build.sh && cd sandbox && ./deploy.sh
EXPOSE 8827 8828 8829
WORKDIR /bfs/sandbox/
CMD ['./start_bfs.sh']
```
报错信息
```shell
make[1]: Entering directory `/bfs/thirdsrc/libunwind-0.99/doc'
latex2man -t ./libunwind.trans unw_destroy_addr_space.tex unw_destroy_addr_space.man
make[1]: latex2man: Command not found
make[1]: *** [unw_destroy_addr_space.man] Error 127
make[1]: Leaving directory `/bfs/thirdsrc/libunwind-0.99/doc'
make: *** [all-recursive] Error 1
The command '/bin/sh -c cd /bfs && ./build.sh && cd sandbox && ./deploy.sh' returned a non-zero code: 2
```

没找到latex2man个包, 源里搜索不到

Start with the Dockerfile and build.sh, then inspect thirdsrc/libunwind-0.99/doc where the build invokes latex2man. Reproduce the CentOS 7 build and trace how that command is expected to be provided; done means the documented Docker build completes without the latex2man error.

Written by the indexing model from the issue text.