[lld] [LLD][COFF] Add support for -includeoptional on ARM64X (PR #126300)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-sles-build-only` running on `rocm-worker-hw-04-sles` while building `lld` at step 9 "Add check check-lld".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/140/builds/16667

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

```
Step 9 (Add check check-lld) failure: test (failure)
******************** TEST 'lld :: COFF/arm64x-includeoptional.s' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 3: /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc -filetype=obj -triple=aarch64-windows /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/lld/test/COFF/arm64x-includeoptional.s -o /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/tools/lld/test/COFF/Output/arm64x-includeoptional.s.tmp.arm64.obj
+ /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc -filetype=obj -triple=aarch64-windows /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.src/lld/test/COFF/arm64x-includeoptional.s -o /home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/tools/lld/test/COFF/Output/arm64x-includeoptional.s.tmp.arm64.obj
/home/botworker/bbot/builds/openmp-offload-sles-build/llvm.build/bin/llvm-mc: error: unable to get target for 'aarch64-unknown-windows-msvc', see --version and --triple.
--

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


```

</details>

https://github.com/llvm/llvm-project/pull/126300