[3.8] bpo-38811: Check for presence of os.link method in pathlib. (GH-17170)

[miss-islington]

Fix also the Path.symplink() method implementation for the case when
symlinks are not supported.
(cherry picked from commit 111772f)

Co-authored-by: Toke Høiland-Jørgensen [email protected]

https://bugs.python.org/issue38811

[the-knights-who-say-ni]

Hello, and thanks for your contribution!

I'm a bot set up to make sure that the project can legally accept this contribution by verifying everyone involved has signed the PSF contributor agreement (CLA).

CLA Missing

Our records indicate the following people have not signed the CLA:

@tohojo

For legal reasons we need all the people listed to sign the CLA before we can look at your contribution. Please follow the steps outlined in the CPython devguide to rectify this issue.

If you have recently signed the CLA, please wait at least one business day
before our records are updated.

You can check yourself to see if the CLA has been received.

Thanks again for the contribution, we look forward to reviewing it!

[miss-islington]

@tohojo and @serhiy-storchaka: Status check is done, and it's a success ✅ .

[miss-islington]

@tohojo and @serhiy-storchaka: Status check is done, and it's a success ✅ .

[miss-islington]

@tohojo and @serhiy-storchaka: Status check is done, and it's a success ✅ .

[vstinner]

I reject this PR because the change in master broke a buildbot:
#17170 (comment)