[BUG] `except *` seems to get interpretted as `except -1` for int return type

[da-woods]

Describe the bug

When a function point is declared with an integer return type, it seems to end up with except ?-1 return type instead. I suspect that this translation is deliberately applied to cdef functions defined in Cython, and erroneously applied to function pointers too

To Reproduce
Code to reproduce the behaviour:

cdef extern from *:
    """
    int g0() {
        PyErr_SetString(PyExc_RuntimeError, "Oh no!");
        return 1;
    }
    """
    cdef int g0() except *

def test():
    cdef int (*fptr)() except *
    fptr = g0
    fptr()

Fails to compile with the error message

    fptr = g0
          ^
------------------------------------------------------------

fptr_cast.pyx:20:11: Cannot assign type 'int (void) except *' to 'int (*)(void) except? -1'

Expected behavior
It should compile

Environment (please complete the following information):

• OS: Linux
• Python version: 3.8.12 (but I doubt it matters)
• Cython version: current master branch

[da-woods]

My current thought is that the test-case in #4689 was failing because of this, but it might work generally. But it needs a bit more investigation first