bug#20536: avoid new gcc warning: ENOTSUP vs EOPNOTSUPP

[Pádraig Brady]

On 09/05/15 19:15, Jim Meyering wrote:
> Building with very new gcc-from-git, I encountered 3 new warnings.
> Here's a patch to address them:
> 
> Without this change, very recent gcc (e.g., version 6.0.0 20150509)
> would print the following when configured with --enable-gcc-warnings:
> 
>   src/copy.c:165:30: error: logical 'or' of equal expressions \
>     [-Werror=logical-op]
>     && (errno == EOPNOTSUPP || errno == ENOTSUP || errno == ENOSYS))
>                            ^
> * src/system.h (is_ENOTSUP): New function.
> * src/copy.c (punch_hole): Use it.
> * src/ls.c (errno_unsupported, gobble_file): Use it.

Not sure I agree with GCC's warning here,
but the fix looks good.

Marking this as done.

thanks!
Pádraig