Bug#724320: gmp: x32: sizeof(mp_limb_t)!=sizeof(void*) is not supported by GAP and PARI

[Torbjorn Granlund]

  I like to clarify that I see this is purely as a Debian issue.
  
And I'd like to clarify that the rest of the world very likely considers
this invalid pari and gap type size assumption as pari and gap bugs, or
at least as a pari and gap portability issue.

This problem has several solutions:

1. Debian and other systems which support PA2.0N, MIPS n32, X86-64 x32
   exclude pari and gap from the x32 (sub-)dist.  Or else just bundle
   plain 32-bit binaries for a ~3-fold performance penalty.
2. Debian and other systems which support any of the above ABIs maintain
   local pari and gap patches to fix the invalid type size assumption.
3. The pari and gap teams fix the invalid type size assumption
   themselves.

1 is simplest, 3 would be best, 2 might be hard and unmaintainable.

(I believe PA2.0N is mostly irrelevant since PA is obsolete and since
the kernel Linux doesn't support PA2.0.  MIPS n32 is highly relevant,
though.  And x32 is highly relevant too of course.)

-- 
Torbjörn