Add unit test coverage for RPATH correctness

[ScottTodd]

Forking from #5108 (comment)

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Original report (from Claude Code): https://github.com/ScottTodd/claude-rocm-workspace/blob/main/reviews/pr_TheRock_5108.md#unit-test-coverage-for-rpath-correctness

Current state

There is no automated validation of RPATH correctness. The existing
therock_test_validate_shared_lib / validate_shared_library.py only checks
that a .so can be dlopen'd — it doesn't verify executable RPATH entries.

Proposed: RPATH validation script

A post-build validation script could catch these issues at CI time rather than
waiting for runtime failures. Approach:

# build_tools/validate_rpath.py
# Walk dist/<subproject>/stage/, find all ELF executables/shared libs,
# read RUNPATH via readelf/pyelftools, verify each $ORIGIN-relative
# path resolves to a directory that actually exists in the stage tree.

This could be wired up similar to therock_test_validate_shared_lib:

# cmake/therock_testing.cmake
function(therock_test_validate_rpath)
  # For each ELF binary in the dist tree, verify RPATH entries resolve
  add_test(
    NAME therock-validate-rpath-${subproject}
    COMMAND "${Python3_EXECUTABLE}"
      "${THEROCK_SOURCE_DIR}/build_tools/validate_rpath.py"
      "${dist_path}"
  )
endfunction()

Alternative: CMake-time validation

A lighter approach: add validation in therock_global_post_subproject.cmake
that compares the target's actual install destination (from RUNTIME_OUTPUT_DIRECTORY
or the install() command) against the computed origin. This is tricky because
CMake doesn't reliably expose the install destination as a target property at
configure time — it's set in the install() command, which is a separate
code path.

Recommendation

The script approach is more practical. It could run as a CTest after
ninja install and would catch:

1. Missing THEROCK_INSTALL_RPATH_ORIGIN for non-standard install locations
2. Missing INSTALL_RPATH_DIRS for non-standard lib directories
3. Stale RPATH entries pointing to nonexistent directories

---

(back to my words)

The ctest after ninja install would just be the existing

TheRock/.github/workflows/multi_arch_build_portable_linux_artifacts.yml

Lines 179 to 181 in 8d042a2

	- name: Test Packaging
	run: |
	ctest --test-dir ${BUILD_DIR} --output-on-failure