[llvm] [SPIRV] Fix APInt overflow in memset constant array creation (PR #180189)

[Nick Sarnie via llvm-commits]

sarnex wrote:

The issue is not related to this change. It's a sporadic `libomp` issue, already reported [here](https://github.com/llvm/llvm-project/issues/176451).

https://github.com/llvm/llvm-project/pull/180189