[llvm] [llvm-debuginfo-analyzer] Fix crash with WebAssembly dead code (PR #141616)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-amdgpu-runtime-2` running on `rocm-worker-hw-02` while building `llvm` at step 8 "Add check check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/8094

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

```
Step 8 (Add check check-llvm) failure: test (failure)
******************** TEST 'LLVM :: tools/llvm-debuginfo-analyzer/WebAssembly/wasm-32bit-tombstone.s' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-mc -arch=wasm32 -filetype=obj                /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/test/tools/llvm-debuginfo-analyzer/WebAssembly/wasm-32bit-tombstone.s                 -o /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/test/tools/llvm-debuginfo-analyzer/WebAssembly/Output/wasm-32bit-tombstone.s.tmp.wasm-32bit-tombstone.wasm # RUN: at line 27
+ /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-mc -arch=wasm32 -filetype=obj /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/test/tools/llvm-debuginfo-analyzer/WebAssembly/wasm-32bit-tombstone.s -o /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/test/tools/llvm-debuginfo-analyzer/WebAssembly/Output/wasm-32bit-tombstone.s.tmp.wasm-32bit-tombstone.wasm
/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-mc: error: invalid target 'wasm32'.
--

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


```

</details>

https://github.com/llvm/llvm-project/pull/141616