Add symbol visibility checks

[bdice]

Summary

• Adds a ci/check_symbols.sh exported-symbol guard modeled on cuDF, with cuOpt-specific forbidden internal namespace patterns.
• Wires the symbol check into the libcuopt conda recipe after installing libmps_parser and libcuopt.
• Starts hidden-by-default symbol visibility treatment by adding export macros for libcuopt C API and libmps_parser parser/writer APIs.

Status

This is intentionally opened as a draft. The new guard is useful, but libcuopt.so still exports CUB/Thrust/RAFT/RMM and cuOpt detail symbols after the initial hidden-visibility pass.

Validation

• cmake --build /home/coder/cuopt/cpp/build/latest --target mps_parser cuopt -j 8 passed.
• ./ci/check_symbols.sh /home/coder/cuopt/cpp/build/latest/libmps_parser/libmps_parser.so passed.
• ./ci/check_symbols.sh /home/coder/cuopt/cpp/build/latest/libcuopt.so currently fails as expected; first failing pattern is cub:: with 1910 matches in the rebuilt library.
• C API exports remain visible in the rebuilt libcuopt.so (cuOptCreateProblem, cuOptGetFloatSize, cuOptSolve, cuOptDestroySolution).

References

• Closes Hide internal C++ symbols exported from libcuopt #1213 when complete.
• Related: rapidsai/build-infra#53.
• Examples: Fix symbol export rapidsai/cuml#8037, Hide visibility of non public symbols rapidsai/cudf#15982, Fix symbol export rapidsai/raft#3006, Explicitly mark RMM headers with RMM_EXPORT rapidsai/rmm#1654.

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[bdice]

Update: split the visibility work from the CUDA template-stub work.

Committed a4664278 with visibility-only fixes:

• Keeps -static-global-template-stub=false in place for now; no .cu include workaround remains.
• Applies hidden visibility to libcuopt only when BUILD_TESTS=OFF, so package builds get hidden symbols while developer/test builds can continue linking internal tests.
• Adds explicit exports for installed/public C++ surfaces needed by cuopt_cli, cuopt_grpc_server, gRPC mappers/client, CPU problem/solution types, settings, and mps_parser public classes.

Validation:

• build-cuopt-cpp -j0 passes.
• build-cuopt-cpp -j0 -DBUILD_TESTS=OFF --target cuopt cuopt_cli cuopt_grpc_server passes.
• ./ci/check_symbols.sh cpp/build/latest/libmps_parser/libmps_parser.so passes.
• ./ci/check_symbols.sh cpp/build/latest/libcuopt.so still fails on cub:: in the package-style build; that is the separate CUDA template-stub issue to fix next without including .cu files.

[bdice]

Update: fixed the CUDA template-stub portion without including .cu files.

Committed e04db5c5:

• Removed -static-global-template-stub=false.
• Added host wrapper functions around cross-TU templated CUDA kernels so kernel addresses are taken/launched in the same .cu that defines them.
• Updated feasibility-jump and insertion/ejection launch sites to use wrappers.
• No .cu source includes were added.

Reference pattern from rapidsai/cudf#14726: CUDA kernels should have internal/hidden linkage rather than relying on externally visible template stubs.

Validation:

• build-cuopt-cpp -j0 -DBUILD_TESTS=OFF --target cuopt cuopt_cli cuopt_grpc_server passes.
• build-cuopt-cpp -j0 passes.
• Hidden package build symbol counts: cub:: 0, thrust:: 0.
• ./ci/check_symbols.sh cpp/build/latest/libmps_parser/libmps_parser.so passes.
• ./ci/check_symbols.sh cpp/build/latest/libcuopt.so now advances past cub::/thrust:: and fails on raft::; that is the next remaining visibility category.

[bdice]

Update: refactored C++ exports to namespace-level annotations in 2563e8fd.

Details:

• Kept the C API function-level CUOPT_EXPORT annotations.
• Changed public C++ API headers to use namespace-level export syntax compatible with GCC, e.g. namespace cuopt { namespace CUOPT_EXPORT linear_programming { ... } }.
• Changed public mps-parser headers to namespace cuopt { namespace MPS_PARSER_EXPORT mps_parser { ... } }.
• Removed most scattered class/function-level exports from those C++ declarations.

Validation after this refactor:

• build-cuopt-cpp -j0 -DBUILD_TESTS=OFF --target cuopt cuopt_cli cuopt_grpc_server passes.
• build-cuopt-cpp -j0 passes.
• Hidden package symbol counts remain cub:: 0, thrust:: 0.
• ci/check_symbols.sh still fails next on raft::, which is the next visibility category.