patch 9.0.1917: undefined behaviour with python function pointer

patch 9.0.1917: undefined behaviour with python function pointer

Problem:  undefined behaviour with python function pointer
Solution: correctly cast function pointers from void

Fix more undefined behaviors in if_python

Fix remaining UBSAN errors from Clang 17 in if_python in casting
function pointers.

Also fix a mistake where `PyMem_Free()` should be returning void, by the
dynamic build is mistakenly casting it as a function that returns an
int.

closes: #13128

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>