Another libio patch

[H.J. Lu]

> 
> What needs to be done so that -lpthread is not needed on linux/glibc2?
>  I have applied the patch to /usr/include/libc-lock.h.  Rebuilding
> libstdc++ doesn't fix it - libstdc++.so still references two symbols
> defined in pthread.  Do I need to rebuild glibc?
> 

That should not happen. With my patch, those 2 symbols should
be weak and ld won't complain.

-- 
H.J. Lu (hjl@gnu.ai.mit.edu)