test protobuf python c++ acceleration

import os
print('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=%s' % os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'))

from google.protobuf.internal import api_implementation
print('API implementation default %s:' % api_implementation._default_implementation_type)
print('API implementation used by protobuf python: %s' % api_implementation.Type())

# this throws if c++ implementation is on and the native extension cannot be loaded
import google.protobuf.timestamp_pb2

print('Success')