bpo-45490: Rename static inline functions (GH-31217)

When a static inline function is wrapped by a macro which casts its
arguments to the expected type, there is no need that the function
has a different name than the macro. Use the same name for the macro
and the function to avoid confusion.

Rename _PyUnicode_get_wstr_length() to PyUnicode_WSTR_LENGTH().

Don't rename static inline _Py_NewRef() and _Py_XNewRef() functions,
since the C API exports Py_NewRef() and Py_XNewRef() functions as
regular functions. The name cannot be reused in this case.

Python/specialize.c

@@ -1939,7 +1939,7 @@ int
     if (PyAsyncGen_CheckExact(iter)) {
         return SPEC_FAIL_FOR_ITER_ASYNC_GENERATOR;
     }
-    PyTypeObject *t = _Py_TYPE(iter);
+    PyTypeObject *t = Py_TYPE(iter);
     if (t == &PyListIter_Type) {
         return SPEC_FAIL_FOR_ITER_LIST;
     }