[VL] Hide symbols defined by gflags for libvelox.so

[PHILO-HE]

What changes were proposed in this pull request?

This is a follow-up pr for this comment.

If not hidden, the below error can be reported when running gluten CPP test.

something wrong with flag 'velox_memory_num_shared_leaf_pools' in file '/__w/incubator-gluten/incubator-gluten/ep/build-velox/build/velox_ep/velox/flag_definitions/flags.cpp'.  One possibility: file '/__w/incubator-gluten/incubator-gluten/ep/build-velox/build/velox_ep/velox/flag_definitions/flags.cpp' is being linked both statically and dynamically into this executable.
CMake Error at /usr/local/lib64/python3.9/site-packages/cmake/data/share/cmake-3.28/Modules/GoogleTestAddTests.cmake:112 (message):
Error running test executable.

  Path: '/__w/incubator-gluten/incubator-gluten/cpp/build/velox/tests/velox_shuffle_writer_test'

velox_memory_num_shared_leaf_pools is declared in Velox under google namespace. See DEFINE_int32 used by this velox code. Even though local: *; is defined for version script, we have to explicitly make all symbols under *google::* namespace hidden. The possible reason is that the specified global *facebook::velox::* symbols cover those *google::* symbols.

How was this patch tested?

CI.

[github-actions]

Thanks for opening a pull request!

Could you open an issue for this pull request on Github Issues?

https://github.com/apache/incubator-gluten/issues

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

[GLUTEN-${ISSUES_ID}][COMPONENT]feat/fix: ${detailed message}

See also:

• Other pull requests

[PHILO-HE]

@zml1206, could you take a look? This is a follow-up for a comment in your merged pr.

[zml1206]

LGTM, thank you.

[PHILO-HE]

Just found some other issue. Let's hold on.