remove *_INTERNED opcodes from marshal

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2017-09-07.04:54:12.645>
labels = ['interpreter-core', 'type-feature', '3.7']
title = 'remove *_INTERNED opcodes from marshal'
updated_at = <Date 2018-07-11.07:58:22.225>
user = 'https://github.com/benjaminp'

bugs.python.org fields:

activity = <Date 2018-07-11.07:58:22.225>
actor = 'methane'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2017-09-07.04:54:12.645>
creator = 'benjamin.peterson'
dependencies = []
files = []
hgrepos = []
issue_num = 31377
keywords = []
message_count = 8.0
messages = ['301569', '301571', '301572', '301576', '301592', '301593', '301594', '321413']
nosy_count = 3.0
nosy_names = ['benjamin.peterson', 'methane', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue31377'
versions = ['Python 3.7']