Fix type size mismatches for MinGW builds

[stefano-p]

Fix pointer type definitions for MinGW 64-bit compatibility

Addresses compilation failures on MinGW x86 and MSVC2019 builds.

[stefano-p]

At least Windows/mingw x86 checks are now all successful.
However, Windows/MSVC2019 still fail.
Waiting for all the builds to complete to have a full report and better analyse logs.

[stefano-p]

Build Issues Fix

✅ MinGW builds fixed! All MinGW compilation errors have been resolved.

❌ MSVC2019_latest. The installation of Visual Studio 2019 fails.
❌ MSVC2019 macro issue identified: The remaining failures appear to be related to the variadic macro system (FIXED2_CHOOSER) not working correctly on MSVC2019. The macro expansion for CHECK_EQ(a,b) incorrectly results in CHECK_EQ_() with no arguments, causing cascading compilation errors.

This issue was likely introduced with the variadic macro improvements in PR #40.
The MSVC2019 preprocessor seems to handle the macro argument counting differently than other compilers.

Should we investigate the MSVC2019 compatibility of the GET_64TH_ARG and MACRO_CHOOSER system, or would you prefer a different approach?

[stefano-p]

There is something wrong with some workflows. For example, MSVC2017 (Release, Win32) is endlessly running and is blocking all the others.