bpo-40170: PyType_HasFeature() now always calls PyType_GetFlags() (GH-19378)

PyType_HasFeature() now always calls PyType_GetFlags() to hide
implementation details. Previously, it accessed directly the
PyTypeObject.tp_flags member when the limited C API was not used.

Add fast inlined version _PyType_HasFeature() and _PyType_IS_GC()
for object.c and typeobject.c.