Add unordered_map include to guard.cpp

[larryliu0820]

Fix some toolchain issue complaining std::unordered_map not available.

Summary

[PLEASE REMOVE] See CONTRIBUTING.md's Pull Requests for ExecuTorch PR guidelines.

[PLEASE REMOVE] If this PR closes an issue, please add a Fixes #<issue-id> line.

[PLEASE REMOVE] If this PR introduces a fix or feature that should be the upcoming release notes, please add a "Release notes: " label. For a list of available release notes labels, check out CONTRIBUTING.md's Pull Requests.

Test plan

[PLEASE REMOVE] How did you test this PR? Please write down any manual commands you used and note down tests that you have written if applicable.

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/15077

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❗ 1 Active SEVs

There are 1 currently active SEVs. If your PR is affected, please view them below:

• [ROCm][CI] Machines under the label linux.rocm.gpu.2 are undergoing maintenance.

❌ 4 New Failures, 3 Pending, 2 Unrelated Failures

As of commit f199b38 with merge base a7d4c5b ():

NEW FAILURES - The following jobs have failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 0b0548b31be56763230e6b7e48e39cd0cde7d4fb4a1693eb7ffe301723681be7 /exec failed with exit code 139
• pull / test-qnn-wheel-packages-linux (3.10) / linux-job (gh)
  RuntimeError: Command docker exec -t 8f8001a2ced06652e9385b7744c64e381cc8a5ed2cb9581698a0ac982adb8ca1 /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.11) / linux-job (gh)
  RuntimeError: Command docker exec -t 634f9ef35d08a5b522ba6da00da269a795655083e6281e30af8e19073d1cf33e /exec failed with exit code 1
• pull / test-qnn-wheel-packages-linux (3.12) / linux-job (gh)
  RuntimeError: Command docker exec -t 9d9fd91f98852a824c914e40e5ed63451e3a1515fb0bbf613e99f36517d5fccb /exec failed with exit code 1

BROKEN TRUNK - The following jobs failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / unittest / windows / windows-job (gh) (trunk failure)
  runtime/test/test_runtime_etdump_gen.py::RuntimeETDumpGenTest::test_etdump_params_with_bytes_and_buffer
• pull / unittest-editable / windows / windows-job (gh) (trunk failure)
  runtime/test/test_runtime_etdump_gen.py::RuntimeETDumpGenTest::test_etdump_params_with_bytes_and_buffer

This comment was automatically generated by Dr. CI and updates every 15 minutes.