gh-93649: Fix linkage of _PyTestCapi_Init_Vectorcall

[arhadthedev]

Addresses this:

##[warning]D:\a\cpython\cpython\Modules_testcapi\vectorcall.c(233,42): warning C4273: '_PyTestCapi_Init_Vectorcall': inconsistent dll linkage [D:\a\cpython\cpython\PCbuild_testcapi.vcxproj]
D:\a\cpython\cpython\Modules_testcapi\parts.h(3,17): message : see previous definition of '_PyTestCapi_Init_Vectorcall' (compiling source file ..\Modules_testcapi\vectorcall.c) [D:\a\cpython\cpython\PCbuild_testcapi.vcxproj]

A follow-up to gh-94549 so cc @encukou.

• Issue: Split up _testcapimodule.c #93649

[arhadthedev]

Hm...

error C2491: '_PyTestCapi_Init_Vectorcall': definition of dllimport function not allowed

In Python\getargs.c this works perfectly:

PyAPI_FUNC(int)
_PyArg_Parse_SizeT(PyObject *args, const char *format, ...)
{

Do we need to declare such an internal function as importable/exportable?

[arhadthedev]

I've made the function non-exportable, now it links with no error.

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @encukou for commit e0670d6 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[encukou]

Thank you!