bug#39236: [musl] coreutils cp mishandles error return from lchmod

[Florian Weimer]

* Paul Eggert:

> On 1/22/20 2:05 PM, Rich Felker wrote:
>> I think we're approaching a consensus that glibc should fix this too,
>> so then it would just be gnulib matching the fix.
>
> I installed the attached patch to Gnulib in preparation for the upcoming 
> glibc fix. The patch causes fchmodat with AT_SYMLINK_NOFOLLOW to work on 
> non-symlinks, and similarly for lchmod on non-symlinks. The idea is to 
> avoid this sort of problem in the future, and to let Coreutils etc. work 
> on older platforms as if glibc 2.32 (or whatever) is already in place.

The lchmod implementation based on /proc tickles an XFS bug:

  <https://sourceware.org/ml/libc-alpha/2020-02/msg00467.html>