Fix manpage auto-discovery links for gnubin-enabled formulae

[gromgit]

Followup to #35874, which no longer works because the macOS man discovery logic seems to have changed. The new link location (.../gnubin/man) works across macOS and Linux man.

This PR depends on Homebrew/brew#17633 to properly function for most users.

Closes #176037.

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[injust]

I think you missed libtool and uutils-coreutils (I searched for libexec.install_symlink "=> \"man\"").

For libtool, was there a reason for the symlink to exist on macOS but not Linux? That isn't consistent with the other symlinks.

[gromgit]

Thanks for the catch, @injust! I'll update this PR after #176809 is committed, otherwise this one will error out.

[gromgit]

@Homebrew/core, could use some help here. CI is complaining about undeclared cached linkages to acl (no idea how that formula's involved) and "can't bottle gnu-tar because we've already installed it" (chicken-n-egg?).

[Bo98]

The fix for gnu-tar will be to make test-bot to build that first but given its rare to rebuild gnu-tar in a multi-formula PR (this is the first time this has happened in many years) it may just be easier and better use of time to just separate that to another PR.

[gromgit]

separate that to another PR

OK thanks, @Bo98, I'll try that.

[gromgit]

OK, now I'm confused. I dropped gnu-tar from this PR, and the latest commit chain seems to confirm that, so why is test-bot still processing it? Do I need to start a new PR?

[MikeMcQuaid]

Have restarted this to see. CC @carlocab in case you know the answer to @gromgit's question.

[ZhongRuoyu]

Thanks, @gromgit!

[github-actions]

@ZhongRuoyu has requested bottles to be published to this PR.

[ZhongRuoyu]

Rebased to resolve conflicts with 8aa83b3. No rebuild needed.

[Mapuppy09]

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