GH-49789: [C++] Use CMAKE_INSTALL_DOCDIR instead of static share/doc/${PROJECT_NAME}

[kou]

Rationale for this change

CMAKE_INSTALL_DOCDIR is the standard variable for install document directory. Packages use this variable to change install document directory.

What changes are included in this PR?

Use CMAKE_INSTALL_DOCDIR instead of static share/doc/${PROJECT_NAME}

Are these changes tested?

Yes.

Are there any user-facing changes?

Yes.

• GitHub Issue: [C++] Use CMAKE_INSTALL_DOCDIR instead of static share/doc/${PROJECT_NAME} #49789

[github-actions]

⚠️ GitHub issue #49789 has been automatically assigned in GitHub to PR creator.

[Copilot]

Pull request overview

This PR updates Arrow C++’s install configuration to use CMake’s standard documentation install directory variable (CMAKE_INSTALL_DOCDIR) instead of a hard-coded share/doc/${PROJECT_NAME}, improving compatibility with downstream packagers and custom install layouts.

Changes:

• Switch ARROW_DOC_DIR from a static path to ${CMAKE_INSTALL_DOCDIR}.
• Keep existing documentation-related install rules (LICENSE/NOTICE/README) but route them through the standardized docdir variable.

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[kou]

+1

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit 09cc2cf.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 1 possible false positive for unstable benchmarks that are known to sometimes produce them.