[clang] [llvm] [CIR][X86] Implement lowering for sqrt builtins (PR #169310)

[Andy Kaylor via llvm-commits]

andykaylor wrote:

> also, since it's a generic builtin (not X86-specific), I assume it should be implemented in CIRGenBuiltin.cpp rather than CIRGenBuiltinX86.cpp. Right?

Yes. It seems that `BI__builtin_ia32_sqrtph512`, `BI__builtin_ia32_sqrtps512`, and `BI__builtin_ia32_sqrtpd512`. Were left in place by https://github.com/llvm/llvm-project/pull/165682, so we'll still need to handle them in `CIRGenBuiltinX86.cpp` (unless there is a plan to remove them), but the elementwise sqrt handling (along with standard sqrt builtin handling) should be done in `CIRGenBuiltin.cpp`.

https://github.com/llvm/llvm-project/pull/169310