Fix intermittent bus errors in portable pocketfft op on macOS

[metascroy]

This PR applies pocketfft patch for ASAN-compatible aligned_alloc on POSIX systems. The portable aligned_alloc in pocketfft stores metadata at ptr[-1], which conflicts with ASAN's heap redzone and causes intermittent bus errors. This patch uses posix_memalign instead, which is ASAN-compatible.

[pytorch-bot]

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❌ 2 New Failures, 1 Unrelated Failure

As of commit 84e941d with merge base 2a12f1f ():

NEW FAILURES - The following jobs have failed:

• pull / test-samsung-models-linux / linux-job (gh)
  test_inception_v3_fp16
• Test CUDA Builds / test-model-cuda-e2e (mistralai, Voxtral-Mini-3B-2507, quantized-int4-tile-packed) / linux-job (gh)
  RuntimeError: Command docker exec -t 435a25645b553bf85116f598c037ec419500a33425f1e9b9aedce6ef79bb9542 /exec failed with exit code 1

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

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

• pull / test-llama-runner-qnn-linux (fp32, qnn_16a16w, qnn) / linux-job (gh) (trunk failure)

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[manuelcandales]

should we land this upstream instead of having this patch, changing code on the fly?
cc @mergennachin

[mergennachin]

Yeah, let's try upstreaming to https://github.com/mreineck/pocketfft

[metascroy]

I've put up a PR here: mreineck/pocketfft#28, but should it not land in pocketfft for some reason, should we not patch in ET given we're distributing the buggy software?