gmp-impl.h assumes 32-bit unsigned int in fft_table_nk

[Torbjörn Granlund]

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

  We have --disable-fft, maybe the code in gmp-impl.h could be protected
  by WANT_FFT. gmp_uint_least32_t also looks like it is unlikely to
  hurt, and we are already using it for other bitfields in the same
  file.
  
  Those changes could make sense whether we support 16 bit systems or not.

Agreed with both suggestions.  (Our usage of unsigned long as basetype
is not standards conformant, and it might not work on an environment
where int is just 2 bytes.)

-- 
Torbjörn
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