python/cpython

This allows easier Enum construction in unusual cases, such as including dynamic member definitions into a class definition:

# created dynamically
foo_defines = {'FOO_CAT': 'aloof', 'BAR_DOG': 'friendly', 'FOO_HORSE': 'big'}

class Foo(Enum):
    vars().update({
            k: v
            for k, v in foo_defines.items()
            if k.startswith('FOO_')
            })
    def upper(self):
        # example method
        return self.value.upper()

pymain_run_file() no longer encodes the filename: pass the filename
as an object to the new _PyRun_AnyFileObject() function.

Add new private functions:

* _PyRun_AnyFileObject()
* _PyRun_InteractiveLoopObject()
* _Py_FdIsInteractive()

Fix encoding name when running a ".pyc" file on Windows:
PyRun_SimpleFileExFlags() now uses the correct encoding to decode the
filename.

* Add pyrun_file() subfunction.
* Add pyrun_simple_file() subfunction.
* PyRun_SimpleFileExFlags() now calls _Py_fopen_obj() rather than
  _Py_fopen().