Define ssize_t as intptr_t in Windows

[feihongmeilian]

After checking, the modification typedef intptr_t ssize_t; is more suitable as it self-adapts to the platform and won't cause conflicts when combined with asynchronous libuv under Win32.

[michael-grunder]

I don't have or use a Windows machine but from some quick reading it appears this is more correct.

WIN32 -> intptr_t -> __int32
WIN64 -> intptr_t -> __int64

Whereas long long is 64 bits on WIN32.

[feihongmeilian]

Yes, according to my research, the C99 standard specifies that long long occupies at least 8 bytes on 32-bit machines.
However, on ​Win32, ssize_t should inherently occupy ​4 bytes, whereas defining it as long long would force it to ​8 bytes, which violates the semantic meaning of ssize_t. Additionally, this discrepancy could cause conflicts when integrating ​libuv​ for asynchronous operations. Below is libuv's definition for reference:https://github.com/libuv/libuv/blob/v1.x/include/uv/win.h#L26

[feihongmeilian]

This problem surfaced when I was compiling redis-plus-plus. I hope my program can run on Win64, Win32, and Linux. However, on Win32, due to the different definitions of ssize_t in hiredis and libuv, redis-plus-plus fails to compile.
Meanwhile, the information I've looked up shows that libuv's definition better conforms to the semantics of ssize_t, so I submitted this PR.

[michael-grunder]

Sorry if it wasn't clear, I mean this PR seems correct 😄

[michael-grunder]

cc @uglide Let me know if you have any issues. Seems good to me.