[llvm] [AArch64] Define high bits of FPR and GPR registers (take 2) (PR #114827)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `bolt-x86_64-ubuntu-shared` running on `bolt-worker` while building `llvm` at step 6 "test-build-bolt-check-bolt".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/151/builds/3244

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

```
Step 6 (test-build-bolt-check-bolt) failure: test (failure)
******************** TEST 'BOLT-Unit :: Core/./CoreTests/11/23' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/worker/bolt-worker2/bolt-x86_64-ubuntu-shared/build/tools/bolt/unittests/Core/./CoreTests-BOLT-Unit-3389418-11-23.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=23 GTEST_SHARD_INDEX=11 /home/worker/bolt-worker2/bolt-x86_64-ubuntu-shared/build/tools/bolt/unittests/Core/./CoreTests
--

Script:
--
/home/worker/bolt-worker2/bolt-x86_64-ubuntu-shared/build/tools/bolt/unittests/Core/./CoreTests --gtest_filter=AArch64/MCPlusBuilderTester.AliasX0/0
--
/home/worker/bolt-worker2/bolt-x86_64-ubuntu-shared/llvm-project/bolt/unittests/Core/MCPlusBuilder.cpp:76: Failure
Expected equality of these values:
  BV.count()
    Which is: 6
  Count
    Which is: 5


/home/worker/bolt-worker2/bolt-x86_64-ubuntu-shared/llvm-project/bolt/unittests/Core/MCPlusBuilder.cpp:76
Expected equality of these values:
  BV.count()
    Which is: 6
  Count
    Which is: 5



********************


```

</details>

https://github.com/llvm/llvm-project/pull/114827