Make implicit returns explicit in longobject.c (in CHECK_SMALL_INT)

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-08-10.21:07:30.736>
labels = ['interpreter-core', 'type-feature', '3.9']
title = 'Make implicit returns explicit in longobject.c (in CHECK_SMALL_INT)'
updated_at = <Date 2019-09-22.06:41:33.865>
user = 'https://github.com/gnprice'

bugs.python.org fields:

activity = <Date 2019-09-22.06:41:33.865>
actor = 'aeros'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2019-08-10.21:07:30.736>
creator = 'Greg Price'
dependencies = []
files = []
hgrepos = []
issue_num = 37812
keywords = ['patch']
message_count = 36.0
messages = ['349359', '349360', '349376', '349377', '349379', '349414', '349418', '349420', '349425', '349429', '349430', '350352', '350353', '350378', '350380', '350398', '350402', '352670', '352685', '352688', '352689', '352690', '352691', '352693', '352694', '352695', '352709', '352781', '352833', '352834', '352836', '352837', '352838', '352842', '352904', '352963']
nosy_count = 8.0
nosy_names = ['tim.peters', 'rhettinger', 'mark.dickinson', 'vstinner', 'malin', 'Greg Price', 'sir-sigurd', 'aeros']
pr_nums = ['15203', '15216', '15448']
priority = 'normal'
resolution = None
stage = 'resolved'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue37812'
versions = ['Python 3.9']