[paho-mqtt] Fix Windows platform predefined macros

[JackBoosY]

According to msdn documentation, fix predefined WIN32 and WIN64.

Related: #9742.

[JackBoosY]

Regressions will fixed in #9752.

[c72578]

The following code in fix-win-macro.patch introduces redundancy, which is not required:

#if defined(_WIN32) || defined(_WIN64)

The preprocessor macro _WIN32 is defined in both cases (32-bit and 64-bit):

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

So, the following is sufficient (supported by MSVC, GCC, clang):

#if defined(_WIN32)

[JackBoosY]

@c72578 Well, I do this because I want to be as consistent as possible with the source code.