Support linking unnamed temp files into filesystem on Linux

GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2021-09-12.23:45:46.424>
labels = ['type-feature', 'library', '3.11']
title = 'Support linking unnamed temp files into filesystem on Linux'
updated_at = <Date 2021-09-18.01:22:30.534>
user = 'https://bugs.python.org/WGH'

bugs.python.org fields:

activity = <Date 2021-09-18.01:22:30.534>
actor = 'terry.reedy'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-09-12.23:45:46.424>
creator = 'WGH'
dependencies = []
files = []
hgrepos = []
issue_num = 45178
keywords = []
message_count = 1.0
messages = ['401676']
nosy_count = 1.0
nosy_names = ['WGH']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'test needed'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45178'
versions = ['Python 3.11']