*zprintf as overrides

[Bruno Haible]

Hi Paul,

In <https://lists.gnu.org/archive/html/bug-gnulib/2024-04/msg00353.html> you
suggested:

> I'm tempted to use "#define printf zprintf" and leave most of the source
> code alone. Perhaps there should be a Gnulib option for that.

We can do this through one or more gnulib modules.

What I'm wondering is whether it's best to have

* one module per function, i.e.
  - one module for sprintf -> szprintf,
  - one module for snprintf -> snzprintf,
  - one module for vsprintf -> vszprintf,
  - one module for vsnprintf -> vsnzprintf,
  - one module for dprintf -> dzprintf,
  - one module for vdprintf -> vdzprintf,
  - one module for fprintf -> fzprintf,
  - one module for vfprintf -> vfzprintf,
  etc.

* or one module per function group, i.e.
  - one module for *s*printf -> *s*zprintf,
  - one module for *d*printf -> *d*zprintf,
  - one module for *f*printf -> *f*zprintf,

* or one module for all of them together.

And in the first case, what to do if the package requests redirection
of, say, sprintf but then uses vsprintf without redirection? Emit a
warning "vsprintf used but is not 64-bit clean, use vszprintf instead"?

What do you think?

      Bruno