Use cmath functions in kernels/portable

[zingo]

cc @freddan80 @per @oscarandersson8218 @digantdesai

[pytorch-bot]

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🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/17092

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❌ 3 New Failures, 1 Unrelated Failure

As of commit fe96de2 with merge base a06697e ():

NEW FAILURES - The following jobs have failed:

• pull / android / run-emulator (gh)
  The process '/usr/bin/sh' failed with exit code 255
• pull / unittest-buck / linux / linux-job (gh)
  RuntimeError: Command docker exec -t 872e4ad1abd7c8a2831db5935979fca15ff8e2e347ac1ff31a28c1496589b2dd /exec failed with exit code 3
• trunk / test-arm-backend-ethos-u (test_model_smollm2-135M) / linux-job (gh)
  RuntimeError: Command docker exec -t 657128d9143de8303b9dee30ba7eee82d08dee3c7a8eb3eb98069851511fb562 /exec failed with exit code 2

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

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

• pull / unittest-buck / macos / macos-job (gh) (trunk failure)
  RuntimeError: Command bash /Users/ec2-user/runner/_work/_temp/exec_script failed with exit code 3

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[zingo]

Hi @SS-JIA here is a generic PR that is the result of a review comment from @mergennachin in #16340 to handle more cases where std:: was missing :)

[SS-JIA]

LGTM; cc: @manuelcandales since this is related to kernel libraries

[mergennachin]

Thank you for following up