cmake: Explicitly specify `Boost_ROOT` for Homebrew's package #32814

1. 
   hebasto commented at 5:53 PM on June 25, 2025: member

   On macOS, this PR ensures that the Boost package is located at its real path rather than via the symlink in the default prefix.

   A backport to 29.x is required for #32804, as this change prevents contamination of include directories by broad locations such as /usr/local/include or /opt/homebrew/include, which take precedence over Qt’s -iframework flags.

   Below is the relevant change in the configuration logs on my macOS 15.5 x64:

   • master branch @ ead44687483e9c936ba970de890c01d5e7ad3485:

   % cmake -B build
   <snip>
   -- Found Boost: /usr/local/include (found suitable version "1.88.0", minimum required is "1.73.0")
   <snip>
   

   • this PR:

   % cmake -B build
   <snip>
   -- Found Boost: /usr/local/opt/boost/include (found suitable version "1.88.0", minimum required is "1.73.0")
   <snip>
   

   This PR is forward-compatible with the changes proposed in #32667.

2. cmake: Explicitly specify `Boost_ROOT` for Homebrew's package

   On macOS, this change ensures that the Boost package is located at its
   real path rather than via the symlink in the default prefix.

   8800b5acc1
3. hebasto added the label macOS on Jun 25, 2025
4. hebasto added the label Build system on Jun 25, 2025
5. hebasto added the label Needs backport (29.x) on Jun 25, 2025
6. 
   DrahtBot commented at 5:53 PM on June 25, 2025: contributor

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   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

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   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32814.

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   Conflicts

   Reviewers, this pull request conflicts with the following ones:

   • #32667 (build: Find Boost in config mode by hebasto)

   If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

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7. hebasto added this to the milestone 29.1 on Jun 26, 2025
8. 
   fanquake commented at 1:10 PM on June 26, 2025: member

   cc @purpleKarrot

9. 
   purpleKarrot commented at 1:17 PM on June 26, 2025: contributor

   ACK

10. fanquake approved
11. 
    fanquake commented at 1:59 PM on June 26, 2025: member

    ACK 8800b5acc1ef7abe6c5260ae0be5386b1d593a19 Checked that this plus #32805 fixes #31009

12. fanquake merged this on Jun 26, 2025
13. fanquake closed this on Jun 26, 2025

    ---

14. fanquake referenced this in commit a3c1939d6e on Jun 26, 2025
15. fanquake removed the label Needs backport (29.x) on Jun 26, 2025
16. 
    fanquake commented at 2:03 PM on June 26, 2025: member

    Backported to 29.x in #32810.

17. hebasto deleted the branch on Jun 26, 2025
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Milestone
29.1