GMP prototypes

[Torbjorn Granlund]

Marc Glisse <marc.glisse at inria.fr> writes:

  * we say that gmpxx requires gcc-2.91+ but I am not even sure we
  tested the latest release with gcc-2.95, it is probably better to just
  remove this precision and stick to "reasonably recent".
  
Agreed.  :-)

  * we document get_mpz_t as returning an mpz_t (it returns an mpz_ptr),
  which could confuse users since IIRC we explain elsewhere that one
  cannot return an mpz_t. I hesite between: 1) do nothing, 2) document a
  return type of mpz_t& even though that's a lie, and 3) something
  else. 1) for now ;-)

IIRC, it has been brought up before about documenting mpz_ptr (and not
long ago by Niels).  I cannot recall if we made any decision.

-- 
Torbjörn