[llvm] [SelectOpt] Optimise big select groups in the latch of a non-inner loop to branches (PR #119728)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vls-2stage` running on `linaro-g3-02` while building `llvm` at step 6 "build stage 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/4/builds/4387

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

```
Step 6 (build stage 1) failure: 'ninja' (failure)
...
[7740/8796] Linking CXX static library lib/libMLIRFuncToSPIRV.a
[7741/8796] Linking CXX static library lib/libMLIRSCFTransformOps.a
[7742/8796] Linking CXX static library lib/libMLIRIndexToSPIRV.a
[7743/8796] Linking CXX static library lib/libMLIRUBToSPIRV.a
[7744/8796] Linking CXX static library lib/libMLIRMemRefToSPIRV.a
[7745/8796] Linking CXX static library lib/libMLIRMathToSPIRV.a
[7746/8796] Linking CXX static library lib/libMLIRArithToSPIRV.a
[7747/8796] Building CXX object tools/flang/lib/Semantics/CMakeFiles/FortranSemantics.dir/canonicalize-do.cpp.o
[7748/8796] Linking CXX static library lib/libMLIRSCFToSPIRV.a
[7749/8796] Linking CXX static library lib/libMLIRVectorToSPIRV.a
command timed out: 1200 seconds without output running [b'ninja'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3616.097244

```

</details>

https://github.com/llvm/llvm-project/pull/119728