Removed unnecessary _WIN64 conditional checks

[fpagliughi]

Minor nit to start some cleanup....

The _WIN64 preprocessor macro is always defined by the Microsoft compiler when _WIN32 is defined. So you don't need to check if one or the other is defined. You can just check for _WIN32.

#if defined(_WIN32)
    // Windows code (32 or 64-bit)
#else
    // Non-windows code (Linux, macOS, etc)
#endif

If you need code specific for 32-bit vs 64-bit, you need need to check for _WIN64 first/else, or nest it, like:

#if defined(_WIN32)
    #if defined(_WIN64)
        // Windows 64-bit code
    #else
        // Windows 32-bit code
    #endif
#else
    // Non-windows code (Linux, macOS, etc)
#endif

but we're not making that distinction here. To just check if we're on Windows, checking for _WIN32 is sufficient.

From the Microsoft documentation:

• _WIN32 Defined as 1 when the compilation target is 32-bit ARM, 64-bit ARM, x86, or x64. Otherwise, undefined.

• _WIN64 Defined as 1 when the compilation target is 64-bit ARM or x64. Otherwise, undefined.

https://learn.microsoft.com/en-us/cpp/preprocessor/predefined-macros?view=msvc-170