[llvm] [SPIRV] Start adding support for `int128` (PR #170798)

[Manuel Carrasco via llvm-commits]

mgcarrasco wrote:

@AlexVlx The PR fixes this failing test case I had. Would it be worth adding it? It does test a different int width.

```
target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n32:64-S32-G1-P4-A0"
target triple = "spirv64-amd-amdhsa"

define spir_func i72 @_Z1dv() addrspace(4) {
entry:
  ret i72 0
}
```


https://github.com/llvm/llvm-project/pull/170798