PATCH] int128: Check __SIZEOF_INT128__ instead of __WORDSIZE == 32

[Wilco Dijkstra]

Hi HJ,

> checks __WORDSIZE == 32 to decide if int128 can be used, which breaks
> x32 which has int128 and __WORDSIZE == 32.  Check __SIZEOF_INT128__,
> instead of __WORDSIZE == 32, for int128.  This fixes BZ #33677.

Checking __SIZEOF_INT128__ seems wrong like checking __WORDSIZE.
The correct check is surely BITS_PER_MP_LIMB == 32?

Cheers,
Wilco