[llvm] [SPIRV] Fix crash when two functions share an alias scope (PR #225017)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx-nvidia-win` running on `as-builder-8` while building `llvm` at step 7 "test-build-unified-tree-check-llvm".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/54/builds/23833

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

```
Step 7 (test-build-unified-tree-check-llvm) failure: test (failure)
...
PASS: LLVM :: Analysis/AliasSet/unknown-inst-tracking.ll (8 of 71143)
llvm-lit.py: C:\buildbot\as-builder-8\llvm-nvptx-nvidia-win\llvm-project\llvm\utils\lit\lit\main.py:283: error: a worker process crashed: A process in the process pool was terminated abruptly while the future was running or pending.

Testing Time: 2.81s

Total Discovered Tests: 71143
  Skipped: 71135 (99.99%)
  Passed :     8 (0.01%)

1 error(s) in tests
FAILED: [code=2] test/CMakeFiles/check-llvm C:/buildbot/as-builder-8/llvm-nvptx-nvidia-win/build/test/CMakeFiles/check-llvm 
C:\Windows\system32\cmd.exe /C "cd /D C:\buildbot\as-builder-8\llvm-nvptx-nvidia-win\build\test && C:\Python314\python.exe C:/buildbot/as-builder-8/llvm-nvptx-nvidia-win/build/./bin/llvm-lit.py -vv C:/buildbot/as-builder-8/llvm-nvptx-nvidia-win/build/test"
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/225017