[llvm] [CodeGen] Add widening support for ISD::CTTZ_ELTS (PR #205841)

[Chandana Mudda via llvm-commits]

chandmudda wrote:

> @chandmudda I see a failure on `main` when trying to build `llvm-test-suite/SingleSource/Regression/C/gcc-c-torture/execute/builtin-bitops-1.c` for hexagon.
> 
> Do you think this PR is likely to address this error or should I open an issue to track it?
> 
> ```
> WidenVectorOperand op #0: t6: i32 = cttz_elts t4
> fatal error: error in backend: Do not know how to widen this operator's operand!
> ```

@androm3da Yes, this fixes it. I reproduced the same WidenVectorOperand ... cttz_elts abort on main with a reduced <3 x i32> case; with this patch it compiles cleanly, so no separate issue is needed.

https://github.com/llvm/llvm-project/pull/205841