GH-45396: [C++] Use Boost with ARROW_FUZZING

[kou]

Rationale for this change

We need arrow_testing for ARROW_FUZZING. And arrow_testing needs Boost.

What changes are included in this PR?

Use Boost with ARROW_FUZZING.

Are these changes tested?

Yes.

Are there any user-facing changes?

No.

• GitHub Issue: [C++] ARROW_FUZZING=ON doesn't find Boost #45396

[github-actions]

⚠️ GitHub issue #45396 has been automatically assigned in GitHub to PR creator.

[kou]

+1

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit 76a52c3.

There were 8 benchmark results with an error:

• Commit Run on arm64-t4g-2xlarge-linux at 2025-02-03 03:05:24Z
  • tpch (R) with engine=arrow, format=native, language=R, memory_map=False, query_id=TPCH-03, scale_factor=1
  • tpch (R) with engine=arrow, format=parquet, language=R, memory_map=False, query_id=TPCH-03, scale_factor=1
• and 6 more (see the report linked below)

There were no benchmark performance regressions. 🎉

The full Conbench report has more details.

[pitrou]

This broke test-build-cpp-fuzz:
https://github.com/ursacomputing/crossbow/actions/runs/13125731106/job/36621579172

[kou]

Oh, sorry. I'll fix it.

#45423