tarfile hardlink fallback ignores custom extraction filter rejection via None

[encukou]

When tarfile extracts a link on a system that doesn't support links, it falls back to extracting a member from the archive. In this case, the filter function is run twice: once for the extracted member, and once with name set to the location of the link.
For one of the calls, the return value is ignored. Instead, the member should be skipped if either call returns None.

Linked PRs

• gh-157265: Honor None result of filter for link fallbacks #157266
• [3.10] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157304
• [3.12] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157305
• [3.11] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157306
• [3.14] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157307
• [3.13] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157308
• [3.15] gh-157265: tarfile: Honor None result of filter for link fallbacks (GH-157266) #157309
• gh-157265: Adjust test for Windows #157334