GH-131296: fix clang-cl warning on Windows in socketmodule.h

[chris-eibl]

I think this is a skip news?

• Issue: clang-cl issues many warnings when building on Windows #131296

[chris-eibl]

Strictly speaking, we're in the #else of #ifndef MS_WINDOWS here and we most probably should indent, but I wanted to keep the diff small.

[chris-eibl]

Fix clang-cl warning:

the current #pragma pack alignment value is modified in the included file [-Wpragma-pack] 

This will silence 16 occurrences in https://github.com/python/cpython/actions/runs/14044831663/job/39366560293?pr=131690#step:4:60.

Actually, pshpack1.h takes care of this warning

#if ! (defined(lint) || defined(RC_INVOKED)) #if ( _MSC_VER >= 800&& !defined(_M_I86)) || defined(_PUSHPOP_SUPPORTED) #pragma warning(disable:4103) #if !(defined( MIDL_PASS )) || defined( __midl ) #pragma pack(push,1) #else#pragma pack(1) #endif#else#pragma pack(1) #endif#endif/* ! (defined(lint) || defined(RC_INVOKED)) */

using #pragma warning(disable:4103), but clang-cl only supports disable for some warnings so far (and doesn't support suppress for those few supported, see also #131821 (comment)).

A different approach would be, to entirely get rid of pshpack1.h, since we are in the MS_WINDOWS code path here. We could do a simple #pragma pack(push,1), which clang-cl understands and neither MSVC nor clang-cl would warn about, but

• I wanted to do the minimal needed stuff to silence clang ...
• ... without having to care about other compilers (mingw, etc), which might then be broken (see An include file is needed because various compilers do this in different ways in pshpack1.h)

[chris-eibl]

Must be done after poppack.h, because there the previous packing is restored and we'd get the same [-Wpragma-pack] warning.

[python-cla-bot]

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[chris-eibl]

@zooba May I ask you for a review?