Make check fail on GMP-6.3.0 after installing macOS Sonoma 14.0 (23A344)

[Torbjörn Granlund]

We are not in a position to debug this, as we don't have recent enough
Mac x86 hardware for running recent enough macos to run these later
problematic Apple compilers.  No, I am not making this up, Apple likes
to play these games with what is supported where.

An educated guess is that this is an Apple/clang compiler bug.  GMP has
triggered countless clang bugs over the years.

-- 
Torbjörn
Please encrypt, key id 0xC8601622