[PATCH] io: Use gnulib fts implementation (BZ 22944, BZ 20331)

[Florian Weimer]

* Bruno Haible:

> Adhemerval Zanella wrote:
>>  create mode 100644 io/cycle-check.c
>>  create mode 100644 io/cycle-check.h
>>  create mode 100644 io/dev-ino.h
>>  create mode 100644 io/fts-cycle.c
>>  create mode 100644 io/hash.c
>>  create mode 100644 io/hash.h
>>  create mode 100644 io/i-ring.c
>>  create mode 100644 io/next-prime.c
>>  create mode 100644 io/next-prime.h
>>  create mode 100644 io/same-inode.h
>
> That's 10 new files, in a directory that already has 104 C source code files
> (excluding tests), and which exist only for use by the fts.c, fts64.c,
> fts64-time64.c compilation units.
>
> For maintainability, I would suggest to put all these 10 files, and possibly
> also fts.c and fts.h, into a subdirectory of io/.
>
> Like the directory resolv/nss_dns/ under resolv/.
> Or like the directories nss/nss_compat/, nss/nss_db/, nss/nss_files/
> under nss/.

That requires using vpath.  The glibc build system is not really
compatible with that.

We can argue with the choice of io for hash table functionality.
That should probably go into misc.

Thanks,
Florian