[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-dylib` 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/119/builds/3088

<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/12/23' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/home/worker/bolt-worker2/bolt-x86_64-ubuntu-dylib/build/tools/bolt/unittests/Core/./CoreTests-BOLT-Unit-3417609-12-23.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=23 GTEST_SHARD_INDEX=12 /home/worker/bolt-worker2/bolt-x86_64-ubuntu-dylib/build/tools/bolt/unittests/Core/./CoreTests
--

Script:
--
/home/worker/bolt-worker2/bolt-x86_64-ubuntu-dylib/build/tools/bolt/unittests/Core/./CoreTests --gtest_filter=AArch64/MCPlusBuilderTester.AliasSmallerX0/0
--
/home/worker/bolt-worker2/bolt-x86_64-ubuntu-dylib/llvm-project/bolt/unittests/Core/MCPlusBuilder.cpp:76: Failure
Expected equality of these values:
  BV.count()
    Which is: 3
  Count
    Which is: 2


/home/worker/bolt-worker2/bolt-x86_64-ubuntu-dylib/llvm-project/bolt/unittests/Core/MCPlusBuilder.cpp:76
Expected equality of these values:
  BV.count()
    Which is: 3
  Count
    Which is: 2



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


```

</details>

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