[llvm] [SCEV] Avoid overflow in howManyGreaterThans. (PR #217744)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-nvptx64-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/155/builds/22939

<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)
...
  Passed           :  3737 (5.37%)
  Expectedly Failed:    12 (0.02%)

1 error(s) in tests
X executable unittests\IR\IRTests.exe
[899/903] Linking CXX executable unittests\Transforms\Scalar\ScalarTests.exe
[900/903] Linking CXX executable unittests\Target\X86\X86Tests.exe
[901/903] Building CXX object unittests\ObjectYAML\CMakeFiles\ObjectYAMLTests.dir\DXContainerYAMLTest.cpp.obj
[902/903] Linking CXX executable unittests\ObjectYAML\ObjectYAMLTests.exe
[902/903] Running the LLVM regression tests
FAILED: test/CMakeFiles/check-llvm C:/buildbot/as-builder-8/llvm-nvptx64-nvidia-win/build/test/CMakeFiles/check-llvm 
C:\Windows\system32\cmd.exe /C "cd /D C:\buildbot\as-builder-8\llvm-nvptx64-nvidia-win\build\test && C:\Python313\python.exe C:/buildbot/as-builder-8/llvm-nvptx64-nvidia-win/build/./bin/llvm-lit.py -vv C:/buildbot/as-builder-8/llvm-nvptx64-nvidia-win/build/test"
ninja: build stopped: subcommand failed.

```

</details>

https://github.com/llvm/llvm-project/pull/217744