[clang] [llvm] [clang][AArch64] Add getHostCPUFeatures to query for enabled features in cpu info (PR #97749)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-4` while building `clang,llvm` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/8413

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

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clang :: Driver/aarch64-mcpu-native.c' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: export LLVM_CPUINFO=/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/Inputs/cpunative/neoverse-v2
+ export LLVM_CPUINFO=/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/Inputs/cpunative/neoverse-v2
+ LLVM_CPUINFO=/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/Inputs/cpunative/neoverse-v2
RUN: at line 3: /Users/buildbot/buildbot-root/aarch64-darwin/build/bin/clang --target=aarch64 --print-enabled-extensions -mcpu=native | /Users/buildbot/buildbot-root/aarch64-darwin/build/bin/FileCheck --strict-whitespace --check-prefix=CHECK-FEAT-NV2 --implicit-check-not=FEAT_ /Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/aarch64-mcpu-native.c
+ /Users/buildbot/buildbot-root/aarch64-darwin/build/bin/clang --target=aarch64 --print-enabled-extensions -mcpu=native
+ /Users/buildbot/buildbot-root/aarch64-darwin/build/bin/FileCheck --strict-whitespace --check-prefix=CHECK-FEAT-NV2 --implicit-check-not=FEAT_ /Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/aarch64-mcpu-native.c
clang version 20.0.0git (https://github.com/llvm/llvm-project.git d732c0b13c55259177f2936516b6087d634078e0)
Target: aarch64
Thread model: posix
InstalledDir: /Users/buildbot/buildbot-root/aarch64-darwin/build/bin
Build config: +assertions
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/aarch64-mcpu-native.c:11:23: error: CHECK-FEAT-NV2: expected string not found in input
// CHECK-FEAT-NV2:    FEAT_BF16                                              Enable BFloat16 Extension
                      ^
<stdin>:6:93: note: scanning from here
    FEAT_AdvSIMD                                           Enable Advanced SIMD instructions
                                                                                            ^
<stdin>:16:5: note: possible intended match here
    FEAT_FP16                                              Enable half-precision floating-point data processing
    ^

Input file: <stdin>
Check file: /Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/test/Driver/aarch64-mcpu-native.c

-dump-input=help explains the following input dump.

Input was:
<<<<<<
            1: Extensions enabled for the given AArch64 target 
check:5        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
not:imp1'0     X
not:imp1'1                                                    X
            2:  
empty:6        ^
not:imp1'2     X
            3:     Architecture Feature(s)                                Description 
check:7            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
not:imp1'2     ~~~~
not:imp1'3                                                                           X
            4:     FEAT_AES, FEAT_PMULL                                   Enable AES support 
check:8            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
not:imp1'3     ~~~~
not:imp1'4                                                                                  X
            5:     FEAT_AMUv1                                             Enable Armv8.4-A Activity Monitors extension 
check:9            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...

```

</details>

https://github.com/llvm/llvm-project/pull/97749