arrow GH-46728: [Python] Skip test_gdb.py tests if PyArrow wasn't built debug

Rationale for this change

As mentioned in #46728, if Arrow C++ was built debug, and PyArrow wasn't, test_gdb.py runs tests that fail.

What changes are included in this PR?

The CMAKE_BUILD_TYPE environment variable is propagated from build into PyArrow, where it's checked to skip unit tests.

Are these changes tested?

Yes. I have built PyArrow in release, debug, and relwithdebinfo and observed the new behavior. Because CMakeLists.txt was changed, I built PyArrow twice via setup.py and pip install, and checked the new function.

Are there any user-facing changes?

Devs may skip unit tests that would fail. PyArrow now has build_info() with information about the build type.

GitHub Issue: #46728

Jun 09 '25 22:06 dinse

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}