"cabal exec hadrian" occasionally segfaults on aarch64

These are the 20 cases I have identified. Earliest is July 1 2022; latest is yesterday November 3 2022.

• https://gitlab.haskell.org/ghc/ghc/-/jobs/1099634
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1102436
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1105489
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1111482
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1112263
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1114802
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1115293
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1117820
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1120348
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1123960
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1130252
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1130817
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1131697
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1134556
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1141363
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1141888
• https://gitlab.haskell.org/ghc/ghc/-/jobs/1220316
• https://gitlab.haskell.org/NicolasT/ghc/-/jobs/1215754

Running hadrian/build-cabal --flavour=validate -j8 --broken-test= --bignum=gmp test --test-root-dirs=testsuite/tests/stage1 --test-compiler=stage1 runtest.opts+=...
[...]
hadrian/build-cabal: line 36: 120399 Segmentation fault      (core dumped) "$CABAL" --project-file="$PROJ" new-exec "${CABFLAGS[@]}" hadrian -- --directory "$PWD" "$@"
hadrian/build-cabal --flavour=validate -j8 --broken-test= --bignum=gmp test --test-root-dirs=testsuite/tests/stage1 --test-compiler=stage1 runtest.opts+= failed
error: hadrian stage1 test

Cheng suggests that it's probably cabal exec that is segfaulting.