[clang] [llvm] [LoongArch] Support LA V1.1 feature that div.w[u] and mod.w[u] instructions with inputs not signed-extended. (PR #116764)

[Lu Weining via cfe-commits]

SixWeining wrote:

> the original test is from gcc
> 
> ```c++
> int divw(long a, long b) { 
>   return (int)a / (int)b; 
> }
> 
> unsigned int divwu(long a, long b) { 
>   return (unsigned int)a / (unsigned int)b; 
> }
> 
> int modw(long a, long b) { 
>   return (int)a % (int)b; 
> }
> 
> unsigned int modwu(long a, long b) { 
>   return (unsigned int)a % (unsigned int)b; 
> }
> ```

Prefer to use simple IR like what I mentioned above.

https://github.com/llvm/llvm-project/pull/116764