some headers not compatible with C90

[petere]

Similar to this issue, some header files in v3.11.0b1 contain inline functions that are not compatible with C90 because they contain declarations after statements. This prevents Python.h from being usable in projects that use a pre-C99 compiler.

Will submit a pull request to show the details.

[erlend-aasland]

Closing as duplicate of gh-92781 – please retarget your PR to that issue; also check if gh-92783 fixed the problem