feeenableexcept is missing on MacOS

[valassi]

feeenableexcept is missing on MacOS...

... and my MR #723 fails the CI

https://github.com/madgraph5/madgraph4gpu/actions/runs/5621540599/job/15232522196

c++  -O3  -std=c++17 -I. -I../../src -I../../../../../test/googletest/install/include -I../../../../../test/googletest/install/include -Wall -Wshadow -Wextra -ffast-math   -march=x86-64  -DMGONGPU_FPTYPE_DOUBLE -DMGONGPU_FPTYPE2_DOUBLE -fPIC -c testxxx.cc -o testxxx.o
testxxx.cc:64:5: error: use of undeclared identifier 'feenableexcept'; did you mean 'feraiseexcept'?
    feenableexcept( FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW ); // debug #701
    ^~~~~~~~~~~~~~
    feraiseexcept
/Applications/Xcode_14.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/fenv.h:299:12: note: 'feraiseexcept' declared here
extern int feraiseexcept(int /* excepts */);
           ^
testxxx.cc:426:5: error: use of undeclared identifier 'fedisableexcept'; did you mean 'feraiseexcept'?
    fedisableexcept( FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW ); // debug #701
    ^~~~~~~~~~~~~~~
    feraiseexcept
/Applications/Xcode_14.2.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/fenv.h:299:12: note: 'feraiseexcept' declared here
extern int feraiseexcept(int /* excepts */);
           ^
2 errors generated.
make: *** [testxxx.o] Error 1
Error: Process completed with exit code 2.

I will have a quick look if I find a way out. But otherwise, I will just disable this. And if ever fortran tests fail on MacOS, I would just disable MacOS as a platform. We do not really need this anyway.

[valassi]

There are a couple of useful pointers here
https://stackoverflow.com/questions/37819235/how-do-you-enable-floating-point-exceptions-for-clang-in-os-x
https://stackoverflow.com/questions/71821666/trapping-floating-point-exceptions-and-signal-handling-on-apple-silicon

But, they do not seem to be straightforward. They would require interactive MacOS tests, which I do not have and cannot be bothered to have now.

@hageboeck @roiser @oliviermattelaer you want to test this otherwise?

I will remove the feenableexcept on MacOS. This means that

• runTest will have more chances of succeeding
• any real issue triggered by Fortran linking in production code has more chances of being undetected and showing up later in production code: if that is the case, and we get a real issue only on Mac, I will disable CI tests on Mac

In any case there are real issues on Linux as #701 is only partially solved...