[llvm] [AArch64] Ensure FPR128 callee-save stack offsets are aligned (PR #184314)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `sanitizer-ppc64le-linux` running on `ppc64le-sanitizer` while building `llvm` at step 2 "annotate".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/72/builds/17475

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 2 (annotate) failure: 'python ../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py' (failure) (timed out)
...
--------------------------------------------------------------------------

Testing Time: 596.59s

Total Discovered Tests: 5322
  Skipped          :   11 (0.21%)
  Unsupported      : 1332 (25.03%)
  Passed           : 3938 (73.99%)
  Expectedly Failed:   41 (0.77%)
@@@BUILD_STEP cleanup@@@
command timed out: 1800 seconds without output running [b'python', b'../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=6796.886759
Step 15 (cleanup_1) failure: cleanup_1 (failure)
@@@BUILD_STEP cleanup@@@

command timed out: 1800 seconds without output running [b'python', b'../sanitizer_buildbot/sanitizers/zorg/buildbot/builders/sanitizers/buildbot_selector.py'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=6796.886759

```

</details>

https://github.com/llvm/llvm-project/pull/184314