libunwind-1.4.0 compile failed due to old linux version

[申震(风桦)]

Dear,

I create an issue on github:
https://github.com/libunwind/libunwind/issues/211

We got problem when compiling libunwind-1.4.0 using our environment. Could you 
make some suggestions?

Thanks a lot!
Zhen

from 阿里邮箱 macOS